Produced by: Lenox Softworks, Inc., 114 Main Street, Lenox, MA Authors: Patrick Cooney, Priscilla Laws and Mark Luetzelschwab.

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2 Produced by: Lenox Softworks, Inc., 114 Main Street, Lenox, MA Authors: Patrick Cooney, Priscilla Laws and Mark Luetzelschwab. Programmed by: Mark Luetzelschwab and Mike Gile. Mac and the Mac logo are trademarks of Apple Computer, Inc., registered in the U.S. and other countries. QuickTime and the QuickTime logo are trademarks used under license. The QuickTime logo is registered in the U.S. and other countries. Microsoft and Windows are registered trademarks of Microsoft Corporation in the United States and/or other countries. VideoPoint, VideoPoint Capture and Lenox Softworks are either registered trademarks or trademarks of Lenox Softworks Inc. Copyright Lenox Softworks, Inc

3 Preface Our collaborative effort to develop tools for two dimensional motion analysis began in the fall of 1987 when we, as student and instructor respectively, worked our way through activities in the first calculus-based Workshop Physics course. A major objective of Workshop Physics courses is to help introductory physics students understand the basis of knowledge in physics as a subtle interplay between observations, experiments, definitions, mathematical description, and the construction of theories. The development of the VideoPoint software and the collection of QuickTime movies distributed with it were motivated by our need to find effective ways to observe and analyze two-dimensional motions in the Workshop Physics activities. Uses of Video Point and the Movie Collection The prototype VideoPoint software was originally developed to allow students to analyze their own digital movies of free fall, projectile motion, and the collisions between pucks on an air table. However, we quickly discovered new ways to use VideoPoint to teach introductory physics. For instance, a video analysis of the electrostatic forces between a charged metal coated ball mounted on a wooden dowel and another hanging from a thread turned out to be an ideal way to verify Coulomb s law with low cost apparatus. By placing dozens of small pucks on an air table we could create macroscopic analogs to the atomic behaviors postulated in the derivation of kinetic theory equations. We have been exhilarated by the enjoyment the students derive from making their own movies and by the educational benefits they derive from analyzing them. For example, when students who have already studied one dimensional kinematics create movies of themselves jumping vertically, we can ask them to find a scale factor for the movie, choose a coordinate system for the data to be collected, and find the vertical component of their acceleration as a function of time. All of these tasks require students to think critically about what they are doing. One student who was puzzled about how to scale a movie exclaimed to her partners, I know! Over here on the movie we have the fake centimeters and over there we have the real centimeters. We just need to figure out how many fake centimeters are in a real centimeter! In a similar vein, when asked to choose an origin for the analysis, students often ask instructors to tell them where the origin should be. We just ask them to pick a location and tell them we'll talk about the implications of their choices after the results are analyzed. Students are surprised to find that the velocities and accelerations don't depend on the location of the origin in an unrotated coordinate system. A few summers ago we began filming physics events and digitizing them in the QuickTime format for colleagues who didn't yet have the computer equipment to create their own digital movies. Although the students still make most of their own movies, we quickly discovered that our growing movie collection was also extraordinarily valuable for in-class exercises, homework assignments, and student projects. VideoPoint analysis has enabled us to develop distinctive approaches to teaching mechanics, kinetic theory, and electrostatics. For instance, we approach our teaching of the center of mass concept differently than we used to. Students are now asked to analyze the motion of the "mass center" of two equal masses which collide. When they discover that this "mass center" moves at a constant velocity, we then suggest that the center of mass of a system of masses can be defined dynamically as a point that moves with a constant velocity. The subsequent analysis of collisions between unequal masses enables students to discover rules for calculating the center of mass of a two-body system for themselves. As soon as the prototype version of VideoPoint had basic features added to it, we began introducing end-of-semester mechanics projects. For these projects, we encouraged students to

4 produce their own movies from scratch or digitize them from existing videodisks or video tapes. During the first year the projects were relatively simple with only one or two moving objects. Students analyzed air puck collisions, the throw of a rotating baseball bat, a shot put trial, or impulse forces between dummies and airbags in automobile crash tests. During that first year two of our physics seniors also used video analysis to study the aerodynamics of Trackball motion. Before long, both students and instructors were clamoring to analyze more complex motions such as a bungee jumper whose descent was being followed by a hand held camera, the motion of the center of mass of a ballet dancer doing a grand jeté, a sweeping camera following a broad jumper through the run up and leap, a drag trial with the car moving off into the distance at an angle, hummingbird flight, and crayfish accelerations. As new ideas for projects emerged, features were added to the software that allows users to scale movies, locate the origin on a frame-by-frame basis when the camera, and hence the background moves, assign masses to points and let the software locate the center of mass of a system, and automatically transform from one coordinate system to another. We also added features to allow users to display point markers in different sizes, shapes, and colors so that VideoPoint could be used in lecture demonstrations. In a snowballing process we began using the new VideoPoint features with our movie collection for exciting homework problems including analyses of how events look from the perspective of different coordinate systems (i.e., Galilean relativity), forces sustained by automobile bumpers, the accelerations associated with amusement park rides, rotational accelerations, pendulum motions, the ascent of a NASA lunar module from the moon, the elements of a 3-1/2 turn-triplereverse somersault dive, the temperature of an air puck "atom" as it loses energy to its environment, and the electric field along the axis of charged rod. Whenever possible, we expect students to extract information from the movies such as initial positions and velocities. We believe these assignments are superior to text book problems because they give students more practice with the application of fundamental definitions. Students completing video assignments also have a better understanding of the phenomena they are working with. The possibilities for the creative use of VideoPoint in introductory physics seem unlimited. Whether you are a teacher or a student, we hope you will enjoy devising new ways to use the VideoPoint Software and movie collection as much as we do. If you have new ideas for VideoPoint features or QuickTime movies, let us know. We have already started a list of new features we would like to include in the next version of the software. If you have access to the Internet you can check from time to time for updates, bug reports, and more QuickTime movies produced informally by students and instructors. The address is Acknowledgments Funding from John Wiley and Sons (arranged by the Physics Editor, Cliff Mills), the National Science Foundation (DUE ), and Dickinson College provided us with the resources needed to begin the reprogramming of our prototype video analysis software. Thus, the programming for the new VideoPoint software started just over a year ago when Mike Gile, a Rensselaer graduate student in electrical and computer systems engineering, spent the summer with us developing cross platform software tools (to allow VideoPoint to work on computers operating under both Windows and Macintosh systems) as well the underlying structure of VideoPoint. He has provided valuable support throughout the project. During this past year as programming progressed we also added movies to our collection thanks to the cooperation of Paul Stokstad of PASCO scientific, David Wilkinson of the Department of Physics at Princeton University, and Michael Wittman and John Lello, physics education graduate students at the University of Maryland. We are grateful to a number of student interns who worked with us for one or more summers between 1991 and 1994 on prototype programming the elements of movie making software and the production of QuickTime movies. They are Chris Boswell, Ryan Davis, Jake Hopkins, Sean LaShell, and Mike King.

5 We would also like to thank Pat Cooney of Millersville University, Wolfgang Christian of Davidson College, Chris Moore a research associate at the University of Nebraska, Bill Ploughe of Ohio State University, Bob Teese of Muskingam College, scores of Workshop Physics students, and a number of other colleagues who served as beta testers at other high schools, colleges, and universities for helpful advice. We also owe a vote of thanks to the crew here at Dickinson who helped us with the final touches on the movie collection and this manual. This crew included research associate Grant Braught who programmed the movie browser; program managers Gail Oliver and Maurinda Wingard; colleagues Ken Laws, Robert Boyle, and Hans Pfister; and student interns Joshua Clapper, Amy Filbin, and Jeremiah Williams. Finally, we would like to thank Nathan Winstanley, Diane Arseneau, Pamela Kott, and Ralph Frisina from Lenox Softworks for their professional work on the package design, CD ROM production details, and User s Guide illustrations, layout, and printing. Mark Luetzelshwab and Priscilla Laws Carlisle, Pennsylvania January 1996

6 Contents Preface...iii Uses of Video Point and the Movie Collection...iii Acknowledgments...iv Contents...vi 1. Introduction Overview...1 VideoPoint software in a Nutshell...1 For Those Who Don t Read Manuals An Introduction to VideoPoint Features Conventions Used in this Manual...1 Menu Choices...1 Macintosh Instructions...1 Windows Instructions...1 Screen Shots Basic Information...2 video points...2 Coordinate Systems...2 Scale Factors...3 Calculations Based on Video Points...3 Movies...3 Where do Movies Come From?...3 VideoPoint Files Getting Started How to Install the Software...5 System Requirements...5 Macintosh Requirements...5 Windows Requirements...5 Installation...5 Macintosh...5 Windows A Typical Analysis...6 Opening VideoPoint...6 A Sample Analysis...6 Setup Screens...6 Playing the Movie...7 Taking Data...8 Scaling the Movie...8 Starting the Scaling Process...8 Graphing Data...10 Creating a Mathematical Model of the Data...10 How to Create a Mathematical Model...11 Viewing the Data in a Table...12 Saving Your Work Functional Description Windows...14 Startup Windows...14 Initial Setup...14 Movie Startup...14 Main Windows...15 The Movie Window...15 Movie Area...16 Current Time Field...16 Movie Controller...16 Play/Pause Button;...16

7 The Edit Icons on Slider Bar...16 Step Buttons...16 Location Field...16 Current Point Field...16 Current Frame Field...17 General Notes on the Movie Window...17 On Screen Data...17 Frame Rates...17 Coordinate System Window...17 Coordinate System Header...18 Coordinate System Header...18 Item/Point Line...18 Drag Box...18 Video Point Series Name...18 Visible Check Box Column [V]...18 Trails Check Box Column[T]...18 Origin Check Box Column[O]...19 Mass Column...19 Series Type...19 Scale...19 Movie Field...19 the Coordinate System Window...20 Cartesian Coordinate System...20 Polar Coordinate System...20 Video Coordinate System...20 Table Window...20 Locating the Movie Frame Corresponding to Table Data...21 Select All Region...21 Select Time Row...21 Select Column...21 Graph Window...21 Locating the Movie Frame Corresponding to a Graph Point...21 Changing a Graph Title...21 Changing Vertical and Horizontal Axes Scales Edit Series Dialog Boxes...22 Common Characteristics of Edit Series Dialogs...22 Name...22 Marker...22 Marker Visible...22 Leave Trails...22 OK...23 Cancel...23 Point Series Dialog...23 Mass...23 Origin...23 Coordinates...24 Data Type...24 Units...24 Angle Range...24 Is an Origin...24 The Origin Dialog...24 Rotate (deg)...25 Scale Item...25 Unchecking the Is an Origin Box...25 The Calculated Items Dialog...25

8 Available Point Series List...26 Available Point Series List...26 Included Point Series List...26 Add >>...26 << Remove...26 Point Series Info...26 New Point Series...27 The Edit Calculated Series Dialogs...27 Distance Dialog...27 Center of Mass Dialog...27 How to Create a Center of Mass Calculation...28 Scale Dialog...29 What Scaling Is...29 Length...31 Designated Point Dialog...32 The Designated Point Dialog...32 Points (2)...33 % along AB...33 % perp AB...33 Drawing...33 Angle Dialog...34 Points (3)...34 Clone Point Series Dialog...34 Count Objects of Interest Utility Dialog Boxes...35 Marker Dialog How to Choose and Apply a Marker Type...37 Point Series (Point):...37 Lines:.i.axis:markers;...37 Change:...38 Vector:...38 Marker Color:...38 Scale Movie Dialog...38 Origin...39 Graph Dialog...39 How to Create a Graph...39 Horizontal Axis...40 Vertical Axis...40 Plot...40 Model Dialog...40 Equation...41 A:, B:, C: and D:...41 Apply...41 Frame Rate Dialog...41 Movie Step Size Dialog...41 Coordinate System Dialog...42 Graph Scale Dialog...42 Change Scale Dialog...42 Clear All... Dialog Menus...43 The Apple Menu (MAC Only)...43 The File Menu...43 New Startup...44 Open Movie...44 Open Saved Data Close Window...44 Save As...44

9 Save...44 Export Data...44 Page Setup...44 Print Window...45 Quit...45 The Edit Menu...45 Edit Selected Series Change Marker Leave/Hide Trails...45 Hide/Show Selection...45 Show All...46 Clear Selection on Frame...46 Clear Selection All Frames...46 Clear Frame...46 Clear All Copy (Movie/Data/Window)...46 Delete Selection...46 Select All...46 The Options Menu...46 Auto Add Points...47 Auto Point Advance...47 Auto Frame Advance...47 Make Point Origin...47 Transform Origin...47 Set Default Origin (Coordinate System)...47 Change Scale Remove Movie Switch Movie...48 The Create Menu...48 Point...48 Origin...48 Center of Mass...48 Distance...48 Scale...49 Clone...49 Angle...49 Designated Point...49 Count...49 The Movie Menu...49 Rewind...49 Scale Movie...49 Set Step Size...49 Select Frame Rate...50 Half Size...50 Normal Size...50 Double Size...50 Fill Screen...50 Keep Aspect Ratio...50 Play All Frames...50 Show Frame Numbers...50 The Window Menu...50 Tile...50 Cascade...51 Hide Window...51 Close All...51 Coordinate Systems...51 Current Movie Window...51

10 Table Window...51 The View Menu...52 Movie...52 Coordinate Systems...52 Data Table...52 New Graph Toggle Background. -MAC...52 Graph Menu...52 Add/Edit Model...52 Visible Legend...53 Moveable Legend The Toolbar How Do I? Get Help...54 Mac...54 Windows Open and Save Files...54 Open a Movie...54 Open a Saved File...54 Open a New Setup...54 Save a File...54 Save a File as a Different Name...55 Export Only the Data to a File...55 Save a File Without the Movie Take Data...55 Take Data by Locating Video Points...55 Move Video Points Select Items...56 Select a Video Point Series...56 Select a Group of Video Points...56 Select a Calculated Video Point Series...56 Select the Next Video Point that Needs to be Located Clear Data/Delete Series...56 Clear the Selected Video Point on a Frame...56 Clear All the Data...57 Clear the Point for All the Frames...57 Delete a Series...57 Delete a Located Video Point Series...57 Delete a Calculated Point Series Edit Series...57 Edit a Series...57 Change the Marker of an Series...57 Change the Name of a Series...58 Change the Mass of a Series...58 Show/Hide a Series...58 Turn a Series Trail On/Off...58 Report Point Series Data in Polar Coordinates...58 Change the Angle Range for a Series Create Items...59 Create a Video Point Series...59 Create an Origin (Coordinate System)...59 Create a Center of Mass Series...59 Create a Designated Point...59 Create an Angle...59 Create a Count...59 Create a Scale (the easy way)...60 Create a Scale (the hard way)...60

11 4.8. Modify or Move Calculated Items...60 Add a Video Point Series to a Calculated Series...60 Remove a Video Point Series from a Calculated Series...61 Move Calculated Points...61 Locate Calculated Points Define Coordinate Systems...61 Coordinate System Origins...61 Create a New Origin...61 Decide where to Locate an Origin...61 Transform an Origin...61 Set the Default Origin...62 Remove an Origin...62 Scale a Coordinate System...62 Create a New Scale...62 Use a Scale with Another Coordinate System...62 Change a Scale...63 Change the Length of a Scale Item...63 Choose Polar or Cartesian Coordinates...63 Rotate a Coordinate System...63 Rotate a Coordinate System...64 Visual Coordinate Rotation...64 Numerical Coordinate Rotation...64 Move a Video Point Series to a Different Coordinate System...65 Move a Video Point Series...65 Remove a Scale from a Coordinate System...65 Replace a Scale in a Coordinate System...66 Scale Movies...66 Choose an Object of Known Length for Scale...66 Change a Scale...66 Change the Known Length of a Scale Item Take Short Cuts...66 Turn Off/On Automatic Movie Frame Advance...66 Turn Off/On Automatic Point Selection View and Analyze Movies...66 Play a Movie...66 Play the Movie at Normal Speed...67 Step Through the Movie...67 Rewind The Movie...67 Change the Display of Elapsed Times between Frames...67 View Movie Frame Times...67 Resize the Movie Window...67 Allow any Aspect Ratio...68 Hide/Show the Frame Numbers...68 Analyze at Series of Movies Made with a Fixed Camera...68 Remove a Movie from a Coordinate System Window...68 Add a Movie to a Coordinate System Window that has No Movie Display Data...68 Show the Table Window...68 Create a New Graph...69 Rescale a Graph...69 Zoom in on a Graph...69 Copy Data to a Spreadsheet What If? Problems...70 I Click on the Movie to Locate a Feature and Nothing Happens Movie Situations...70 The is on an Incline...70

12 To Move an Origin...70 To Rotate an Origin s Coordinate System...70 I Want Data Reported in Two Coordinate Systems?...70 The Camera was Moving when the Movie was Filmed?...71 The Camera Panned so Much that my Origin Disappears...72 How to Define a Coordinate Transformation...73 The Camera Zoomed when the Movie was Filmed?...73 How to Compensate for a Zooming Camera...73 The s are in Two Planes?...74 The Camera had a Zoom Lens or a Wide Angle Lens?...74 I m only Interested in Part of the Movie?...74 The Movie is a Time-Lapse or Slow Frame Sequence...74 It Looks as if a Frame is Missing?...75 I Notice that Som e of the Frames are Duplicated?...75 The Movie is from a Commercial Film Dubbed onto a Videotape?...75 If the commercial video is digitized at 30 fps and recompressed at 24 fps Creating Digital Movies Movie Making Tips...76 Camera...76 Background and Object Colors...76 Lighting...76 Scale...76 Zoom Lens Distortions...76 Marking the Center of Mass...77 Human Interest Video Capture Cards...77 Important Facts about Capture Cards...77 Pixels...77 Analog vs. Digital Video Information...77 Frames per Second (fps)...78 Fields and Frames...78 Dropped Frames...78 Half-Screen Video...78 Digital Compression and Decompression Formats...78 The QuickTime Format...78 Built in QuickTime Codecs...79 Cinepak or Compact Video Codec...79 Apple Video Codec...79 JPEG Codec...79 Indeo Codec...79 Post Compress Video...79 Compressing Video in Real-Time...80 QuickTime for Windows (.mov)...80 Video for Windows (.AVI)...80 Problems with AVI to QuickTime Conversion...80 Modest Cost Cards for PC Compatible Users...80 A Modest Cost Card for Macintosh Users...80 A Low-Cost, Limited-Capability Alternative for Macintosh Users...81 Other Capture Cards Preparing Movies for Use with VideoPoint...81 Creating a Title Frame...81 Cropping and Sizing Movie Frames...81 Reducing the Number of Digitized Frames...81 Creating 60 fps movies Educational Video Tapes and Disks to Digitize...83 The Physics Single-concept Films Collections...83

13 Physics and Automobile Collisions...83 The Physics of Sports The Movie Collection Introduction to the Movies...84 Uses for the Collection...84 Observations about the Collection How the Movies were Digitized...85 Overview...85 Digital Capturing and Cropping...85 Adding Title Screens...85 Post Compression...86 Assignment to VideoPoint Browsing in the Collection...86 How the Movies are Cataloged...86 Title Screens...86 Removing a Title Screen...86 File and Movie Names...86 Categories and Descriptions The Collection...87 About the PASCO Laboratory-Based Movies...87 (Available only if VideoPoint was purchase from PASCO scientific)...87 Credits...87 Marker Carts for the Study of Galilean Relativity...87 Warnings!...87 About the Princeton University Air Table Movies...88 Credits D Collisions and Macroscopic Thermodynamics...88 Caveats!...88 About the University of Maryland Traveling Wave Movies...88 Credits...89 Generating the Waves...89 Caveats!...89 About the Dickinson College Movies...89 About the NASA Rocket and LEM Launch Movies...90 About the Hershey Amusement Park Movies...90 Caveats!...90 The PASCO scientific Movie List...90 The Princeton University Movie List The University of Maryland Movie List The Dickinson College Movie List The NASA Movie List The Hershey Movie List Glossary Index...127

14 Video Point Manual Page 1 1. Introduction 1.1. Overview VideoPoint software in a Nutshell VideoPoint is designed to help you analyze the motion of features or objects of interest in digital video movies. This software will allow you to define characteristics of a series of points you would like to examine on each frame. These characteristics include the name, the size and shape of the marker, the mass, and the coordinate system each point series is associated with. You will also be able to specify the length of objects or distances between features in frames for scaling purposes. In addition to obtaining data via the selection of features or objects of interest on frames, you will be able to define calculated data points such as the location of the center of mass of a system of features or objects. Data that are obtained can be graphed as they are located or calculated. Data can be saved in an electronic file or copied for use with other types of analysis software such as spreadsheets and graphing programs. VideoPoint runs on both the Windows and Macintosh platforms. For Those Who Don t Read Manuals... If you are not a manual reader, the fastest way to get started is to read the entries on "video points" and "coordinate systems" in part 1.3 of this Chapter and then skip to Chapter 2 on Getting Started. An Introduction to VideoPoint Features The VideoPoint software allows you to collect coordinate data by clicking on locations of interest on video images with a mouse. This allows you to study two-dimensional motions by locating, displaying, and analyzing coordinate data obtained from sequences of digitized video frames. You can also study individual electronic images saved as QuickTime movies to determine geometric relationships or count objects of interest. The software has a number of innovative features, many of which are not available in other video analysis packages. It can be operated from either menus or a toolbar. It has drag and drop features and a balloon like help system. Some of the things you can do with the VideoPoint software are summarized in this section Conventions Used in this Manual Menu Choices File->Open Movie... is equivalent to choose Open Movie... from the File menu".! Important Note. These include common errors and information on features that aren t obvious.? Common Question and Answer. These answer some of the questions that arise concerning certain features and methods. Macintosh Instructions The abbreviation MAC is used to denote specific instructions for the Macintosh computer. Windows Instructions The abbreviation WIN is used to denote specific instructions for a Windows PC.

15 Video Point Manual Page 2 Screen Shots Almost all of the screen shots depicted in this manual are from the Macintosh version. The screens shown are functionally equivalent to the Windows version Basic Information video points A "video point" is defined as a location of a feature or object of interest on a single QuickTime movie frame. The software initially stores the (x, y, and t) values of a video point; where x is the distance from the left side of the movie window (in pixels); y is the distance from the bottom of the movie window (in pixels); and t is the elapsed time in seconds since the first frame in the movie was recorded. By themselves, video points are not very interesting. However, the VideoPoint software allows you to make calculations based on these video points.? What is the difference between a video point and VideoPoint software? The term VideoPoint refers to the name of the software while the term video point refers to a point you have located on the frame of a QuickTime movie. Video points are designated by you. For example, if you are looking at a movie of a ball toss, you might be interested in measuring the position of the ball in each movie frame. In order to do this, you would set up the VideoPoint software for one video point per frame, and then click on the location of the ball in each frame in the movie. VideoPoint then stores the information for the series of video points corresponding to the selected locations. Since the data set, consisting of a series of video point coordinates, is stored in screen units (pixels) and is relative to the arbitrary origin of the bottom left of the movie, it isn't terribly useful for analysis. Thus, you have the ability to define various coordinate systems. You can then associate the video points with a coordinate system and determine the position coordinates in the system they are associated with. Coordinate Systems A VideoPoint coordinate system is two-dimensional and consists of an origin, an orientation, and an optional scale factor. In addition, you can designate a coordinate system as either Cartesian or polar. By default, VideoPoint opens a movie with two coordinate systems present. The first coordinate system known as the default system and is initially named the "Origin 1" system. It is a Cartesian system with horizontal and vertical axes and an preselected origin (i.e., Origin 1) near the lower left of the movie window. Initially the units of the coordinates in this system are in pixels. You can easily change the name of this system or scale it so that video points you locate have coordinates in meters or centimeters. You can also move the default system origin and rotate the coordinate axes if you choose. The second coordinate system is VideoPoint's native system, the Video Origin system. This is a Cartesian coordinate system with horizontal and vertical axes and no scaling. The coordinates of the video points located in this system are always in pixels, and the "Video Origin" is always at the bottom-left of the movie. You cannot change the "Video Origin" system in any way. Each video point series that you define has to be associated with a coordinate system. Video points that are associated with the Origin 1 coordinate system have (x, y, t) data saved as coordinates in the "Origin 1" coordinate system.

16 Video Point Manual Page 3? What is the difference between a video point series and an origin? Very little, in fact. An origin is just a video point series with the appropriate Is An Origin check box selected. An origin can be edited and moved just like any other video point series. Every origin defines a different coordinate system. Scale Factors Data stored in pixels is only useful for computers. In order to collect data in real units (i.e., meters), each coordinate system must be scaled. In a sample movie, a meter stick might appear to be about 200 pixels tall. During the scaling process, you need to click on both ends of this meter stick and tell the VideoPoint software that the distance between these two video points (which VideoPoint sees as 200 pixels) is actually 1.00 meters. VideoPoint would then assign a scale factor of 200 pixels/m. You can then associate the scale factor with any of the coordinate systems you have defined. With the combination of the origin location and the scale factor, video point data can be reported in real units relative to any coordinate system. Calculations Based on Video Points You can specify the standard calculation based on two coordinates or two or more video points associated with a given coordinate system. Each of these calculated items is described in depth in the How Do I? chapter. These calculations include: Distance Scale Center of Mass Angle Designated Point The distance between any two video points on a frame. Ratio of a known length (in meters or centimeters) to the distance in pixels between two video points. Calculated center of mass of a collection of video points based on masses associates with a series of video points. Each series of video points can be assigned a different mass. Angle made by lines connecting three video points. Point at a location specified by relative distances between any two video points. Movies Movies are sequences of still images that have been digitized and saved in the QuickTime format. Each image is called a frame. Each frame has a time associated with it that represents the elapsed time since the first frame of the movie was recorded. Where do Movies Come From? Many movies can be found on the VideoPoint CD. These sequences of video frames were recorded using a standard video camera and then later digitized by a computer and transformed into a popular digital format known as QuickTime. With appropriate computer hardware installed

17 Video Point Manual Page 4 in your Macintosh or PC computer, you can create your own QuickTime movies that can be analyzed with VideoPoint. VideoPoint Files Information derived by VideoPoint can be saved in more than one way. The entire data set along with the current window arrangement (including movies, data tables, and graphs) can be saved as a VideoPoint file with the extension.vpt. WIN- VideoPoint files have the extension.vpt MAC- Though the sample files all comply to the DOS file naming convention, you can use any name under 32 characters in length. VideoPoint files contain coordinate data as well as the name and location of the movie. It does NOT save the movie itself in the file, nor does it ever edit the movie. Thus, if you want to open a VideoPoint file later, the movie associated with this file must also be present. The only exception is when you save a template for later analysis of similar movies (See "Save a File Without a Movie" in the "How Do I?" chapter). The data can be copied from the data table into the clipboard and spreadsheet or any other program that accepts a tab-delimited format. The entire data set can also be exported as a tabdelimited text file.

18 Video Point Manual Page 5 2. Getting Started 2.1. How to Install the Software System Requirements Versions of VideoPoint are available for use with either Macintosh computers operating under System 8, 9 or OS X Classic mode, or any PC operating under Windows 98 SE or later versions which have QuickTime installed (included on the CD). No special hardware is needed when VideoPoint is used to analyze digital movies in the QuickTime format. However, if you wish to create your own digital movies for analysis, you will need to add an additional digitizing card that can capture video information in a QuickTime format. A capture card can have a Video Camera, VCR, or Videodisk player attached to it. For more details consult Chapter 6 on Creating Digital Movies for Analysis. Macintosh Requirements For Using VideoPoint G3 or better with system 8.6, QT 6.0 or later (included), 1500 KB of free RAM, 1 MB HD storage for program, and approximately 350KB HD storage per 15 frame QuickTime Movie. Windows Requirements For Using VideoPoint Enhanced 386 PC or better w/windows 98 SE, QuickTime for Windows 6.0 or later (included), 1.5 MB free HD storage for program, and approximately 350KB HD storage per QuickTime Movie (avg.). Installation Macintosh Installing the Video Point Software and QuickTime To install VideoPoint and QuickTime, open the MAC folder on the CD and double click on "Video Point Installer". This will give you the option of installing VideoPoint and QuickTime or just VideoPoint (for machines that already have the latest QuickTime installed). Windows Installing Video Point Software and QuickTime In either the Program Manager or the File Manager, choose File->Run and type "e:\windows\setup" where "e" is the letter of the CD drive. Follow the instructions to install VideoPoint. This will install both VideoPoint (vidpoint.exe) and QuickTime for Windows and will create a VideoPoint program group in the Program Manager.

19 Video Point Manual Page A Typical Analysis The easiest type of movie to analyze is a movie with a single feature of interest that was taken with a camera that does not move or zoom during filming. Let's start by analyzing a ball launched from a fixed table. Opening VideoPoint MAC- Double click on the icon in the finder. WIN- Double click on the Program Item in the VideoPoint group. A Sample Analysis Setup Screens Once VideoPoint is opened the following setup screen will appear. To start, click on "Open Movie... to open the movie you want to analyze. To work with this example you should choose the movie entitled "PRJCTILE.MOV" located in the samples directory. Figure 2-1: The VideoPoint title screen A screen showing the first frame of the movie should appear. You will be invited to enter the number of features or objects that you want to locate on each frame. Since only one ball is launched during this movie, type 1 into the box and hit OK.

20 Video Point Manual Page 7 Figure 2-2: The second screen which allows you to indicate the number of features or objects of interest to be located on each frame of the movie. The movie should appear along with a Coordinate System Window. Initially the Coordinate System Window shows two Cartesian systems; the Origin 1 coordinate system and the Video Origin coordinate system. A single video point series (the one specified in the previous dialog box) called Point s1 has been placed in the Origin 1 coordinate system; Point s1 will report all its data relative to the Origin 1 coordinate system. Figure 2-3: The default working screen showing the movie, coordinate frame and data table windows. Playing the Movie P lay the movie to see what happens by clicking on the play button on the movie controller which is located at the bottom of the screen.

21 Video Point Manual Page 8 Rewind the movie by either dragging the slider on the movie controller back to the beginning the controller or by choosing Movie->Rewind" (Ctrl-R). of! MAC users: Use Command-R instead of Ctrl-R Taking Data Move the cursor over the movie window area. The cursor should look like this:, and the bottom right of the movie window should have the italicized text Point s1. This is the first video point to be located by you in the frame that currently appears in the movie window.! Cursors in the Movie Window If the cursor looks like: that is currently selected., clicking on the movie window will locate the video point If the cursor looks like, you can select a previously located video point and use a drag and drop technique to move it to another location. Move th e cursor so that the ball being launched out of the projectile launcher is centered in the cursor. Click once to locate this video point. The movie will automatically advance to the next frame. Continue clicking on the location of the ball in each frame until the last frame of the movie. You have now collected data for this movie. However, the data are still in pixels since you have not yet scaled the movie. Scaling the Movie This process tells VideoPoint how many screen units (pixels) in the Movie Window are in a meter, a centimeter, or a millimeter in the actual scene. Conveniently, a 1.00 meter long meter stick was placed in PRJCTILE.MOV ; this will be used to scale the movie. Starting the Scaling Process Click on the scale icon in the toolbar. The following dialog box will appear. Figure 2-4: The Scale Movie Dialog Box

22 Video Point Manual Page 9 The length of the scale object (in this case, the meter stick) is known to be 1.00 meter. Enter this value into the Known Length box. Since we want to scale the coordinate system relative to Origin 1, select Origin 1 in the Scale Origin: popup menu. Since the camera did not zoom at the instant when the movie was taken, choose a Fixed scale type. (See Zooming Cameras in the What If? chapter for more information). Once these values have been set, you are ready to begin the scaling process: 1. Click on Continue. 2. Click once on one end of the meter stick. 3. Click once on the other end of the meter stick. Note that three new rows appear on the Coordinate System's Window. Two rows, Scale 1A and Scale 1B, specify the ends of the object that you clicked on. The third line, called Scale 1, stores the ratio of the length of the object relative to the distance between Scale 1A and Scale 1B. Now you have scaled this coordinate system by telling VideoPoint that 1.00 meter is equivalent to the distance (in pixels) between the two video points that you just clicked on.? What are the Scale 1A and Scale 1B video points? These two video points are used by the program to determine the number of pixels between the ends of an object or the distance between two features used for scaling on a video frame. If the actual distance (in meters, centimeters, or millimeters) between the Scale 1A and Scale 1B video points is known, then a scale factor can be determined for the frame. This scale factor is calculated as the ratio between the number of pixels between Scale 1A and Scale 1B and the actual distance between these points specified by you. Moving either of the two scaling video points closer together will decrease the scale factor and moving them farther apart will increase the scale factor.

23 Video Point Manual Page 10 Graphing Data To graph the data that you have collected, click on the graph icon in the toolbar or choose View- >New Graph (Ctrl-G) from the menu bar. The following dialog box will appear. Figure 2-5: The Graph Setup Dialog Box From the left list, choose one value that you want as your horizontal (domain) axis. For this example, choose Time. You can then choose one or more values in the right list for the vertical (range) axis. For this example, choose Point s1: Y. This will plot Y vs. Time for the video point series named, "Point s1". Click Plot to create the graph. It should look something like this: Figure 2-6: A Graph window showing a plot of Point 1Y (m) vs. Time (s) for a projectile Repeat the graph process for an X vs. Time plot for Point s1. Creating a Mathematical Model of the Data Since many of the motions of interest in the study of physics can be described by analytic functions, Video Point has a graphical modeling feature that enables you to try to develop a mathematical model for a motion. You can do this by comparing a graph of the motion to a graph of an equation. For example, in analyzing a movie of a bungee jumper in free fall, you could select a graph of the experimentally determined values of y vs. t. Then you could choose to model the data with a quadratic equation and then match the parabolic line to the data by changing values of the equation coefficients. Is the coefficient of the t 2 term close to 4.9 m/s 2?

24 Video Point Manual Page 11 Figure 2-7: Model of y vs. time for the ball toss. Note that this is a model and not a fit. To complete a model efficiently a user must understand how to recognize the type of function that is needed and how each of the equation parameters affects the mathematical function. Note the Model Equation dialog box that follows. How to Create a Mathematical Model To model Y vs. Time for the projectile in figure 2-6, click on the graph to bring it to the front. Then choose Graph->Add /Edit Model. This will bring up the following dialog box. Figure 2-8: The Modeling Dialog Box Since Y vs. Time is a parabola for this projectile, choose the Quadratic formula. Enter appropriate values in each box that correspond to the constants in the equation. Click on Apply to view your modeled graph (shown as a green line) without closing the dialog box. Once you are satisfied with your model, click OK to close the dialog box. If you entered A:-4.90, B:=2.20, and C:=.330, your model should look something like this:

25 Video Point Manual Page 12 Figure 2-9: A Graph Window showing data points and the line which is a graphical representation of mathematical model of the data. The constant A (for the x^2 term) should be approximately -4.9 since this is a projectile that can be modeled by the equation y = 1/2g*t^2 + vot + xo. Viewing the Data in a Table If you want to view the data that you have taken, click on the table window icon or choose View->Data Table. You can select and copy any portion of the data; clicking on the (x) and (y) headers will select entire columns. Figure 2-10: The Table Window showing the coordinate data of Point Series 1 in Cartesian coordinates

26 Video Point Manual Page 13 Saving Your Work Choose File->Save. Decide where you want to save your file.? What Information is Saved with a File? The file contains all your data and open windows as well as the name and location of the movie file. It does NOT contain or change the movie file. This keeps the file sizes small and allows files to be associated with movies that are stored on read-only networks. You have successfully analyzed a movie with VideoPoint. Congratulations. Now it is time to explore the possibilities of VideoPoint analysis. VideoPoint was designed to be easy to use for the simpler cases but flexible and robust enough to handle complex twodimensional motions. Use this VideoPoint manual to learn how to analyze movies that have more than one video point series, more than one coordinate system, how to move and rotate coordinate systems, zooming cameras, and much more.

27 Video Point Manual Page Functional Description 3.1. This section describes functions of each window, dialog, and menu in the VideoPoint software. In addition, the function of each tool in the VideoPoint toolbar is described. Windows Startup Windows Initial Setup VideoPoint greets you with this initial startup window. Your options are: 1) Open Movie. This, the most common choice, lets you select a movie to analyze. 2) Open Saved Data. This option allows you to open a file with set up information and data that has been saved by VideoPoint. 3) Exit Startup. This option closes the startup window without VideoPoint quitting. 4) Quit. This option quits VideoPoint. Figure 3-1: The VideoPoint Title Screen Movie Startup When you open a movie, this dialog box appears. Choose the number of video point series corresponding to objects or features of interest that you plan to locate on each frame. For example, if the movie shows a ball toss, you will want one video point per frame; if it shows a two-cart collision, you will want two video points per frame; if it shows a collision of four pucks, you will want four video points per frame. In any case, this is just a convenient way of defining the video p oint series that you want to create later. You can define or delete video point series at any time during the analysis.

28 Video Point Manual Page 15 Figure 3-2: The VideoPoint Startup Screen Main Windows Movie Window ToolBar Coordinate System Window Table Window Graph Window Figure 3-3: A typical VideoPoint screen. The Movie Window The movie window displays a frame of the movie as well as any video point markers and lines that have been located and calculated on each frame. The main use of the movie window is data collection and display.

29 Video Point Manual Page 16 Movie Area Current Time Field Movie Controller Location Field re 3-4: The Movie Window. Current Video Point Field Figu Movie Area This area displays the current frame of the movie. You can locate video points on the movie by clicking on the movie. If the video point has already been selected on this frame (and it is visible) you can drag it around the movie to re-locate its position. See the section on Taking Data in the How Do I? chapter. Current Time Field This window displays the current elapsed time of the movie in seconds. Movie Controller Use the movie controller to play, step forward, step backward, or scan through a movie. Play/Pause Button; Press this button once to play the movie. By default, the movie plays by stepping through each frame of the movie. The movie can be forced to play in real time by unchecking Movie->Play All Frames. When the movie is playing, the play button becomes a pause button. Click once on the pause button to stop the movie. Slider Bar Drag the little box (the slider) back and forth to scan through the movie quickly. Clicking on the right of the slider bar will advance the movie frame and clicking on the left will bring up an earlier frame. The left and right bounds of the slider bar default to the ends of the movie. Step Buttons These two buttons step through the movie one frame at a time. Location Field This is the (x, y) or (r, θ) coordinates of the cursor location for the video point to be selected relative to its Cartesian or polar coordinate system. If the video point series is associated with a polar coordinate system, the data are displayed as (r, θ) coordinates. Moving the mouse over the origin of the active coordinate system will cause a (0, 0) to be displayed in this field Current Point Field

30 Video Point Manual Page 17 This field gives the name of the selected video point series or the selected calculated series. Current Frame Field The box on the upper right hand corner displays the current frame number of the movie frame displayed in the movie window and total frame count. General Notes on the Movie Window On Screen Data The visible video point markers on each screen are drawn only when the movie is stopped (and you are not controlling it). For example, the markers are drawn after a single frame step but are not drawn if you hold the step button down. Frame Rates Every QuickTime movie has a time code that can be translated into seconds. By default, VideoPoint reads this time code and uses it for the data. However, there are some situations, such as time-lapse movies and movies taken from commercial video tapes, where you might want to override this time code. Choose Movie->Select Frame Rate to override the default time code. Coordinate System Window The Coordinate System Window displays each coordinate system and the name of its associated video point series. Each coordinate system has an origin; it can also have a scale. Each Coordinate System Window always has a Video Origin coordinate system. This coordinate system holds video point series and items whose data are reported in pixels relative to the bottom left corner of the movie window. Video Point Series Name Item/Point Line Drag Box Coordinate system Header Scale Series Type Movie Field Visible Check Box Column Trails Check Box Column Mass Column Origin Check Box Column Figure 3-5: The Coordinate System Window.

31 Video Point Manual Page 18 Coordinate System Header This header describes the coordinate system. It gives the name of the origin, the current orientation of the x-axis relative to the horizontal, and the scale item and scale factor (if any) that is being used to scale the system from computer units (pixels) to real metric length units (m, cm or mm). Note that the origin listed in the coordinate syste m header is also listed in the Coordinate System Window relative to the Video Origin coordinate system or another coordinate system designated by you. Item /Point Line Each object or feature that has a video point series assigned to it ha s its own line that describes the characteristics of the object or feature. These characteristics (and how to change them on the Coordinate System Window) are listed below. Drag Box If you want to interchange the order of two or more video point series or if you want to associate a video point series with a different coordinate system, click on this area (after the cursor has become a hand) and drag the name of the video point series to its new location. The video point series is always inserted before the video point series on which it is dropped; dropping a video point series name on a coordinate system header will place the video point series first on the list of video point series associated with that coordinate system. (See diagram below.) Figure 3-6: Depiction of a hand moving a video point series from one coordinate system to another. Video Point Series Name The name of the video point series can be anything less than 20 characters. Click once on the name to edit it. You can use the tab key to move to the mass column (if the series is a video point series) or to the next series name. Clicking in this column will also select the corresponding series in the movie window. Visible Check Box Column [V] Clicking here toggles the visibility of the video point marker on the movie frame. This option is convenient when you are working with several video point series thus making it difficult to trace the paths of all of the sets at once. Markers for visible video point series will be drawn on the active movie frame. Invisible point series can still be located and selected, but their markers are invisible. Trails Check Box Column[T] Clicking here toggles the visibility of the trails of the video point series. If this box is checked, the item will draw its video point marker at the correct location for all frames of the movie onto the

32 Video Point Manual Page 19 current frame. This is a nice feature to demonstrate the path of an object such as a projectile. (See Figure 3-7.) Figure 3-7: The movie screen on the left has the trails for Point s1 turned off so that only the marker on the active frame is visible. The movie on the right has the trails for Point s1 turned on so all the markers for the point series are visible. Origin Check Box Column[O] If this box is checked for a video point series or other point-type series, the point series becomes an origin and defines a new coordinate system. Other series can be made relative to this new coordinate system. Unchecking this box will cause the coordinate system that is defined by this origin to be removed. Any series relative to this now default origin will be moved to the video origin coordinate system. Mass Column The mass of each video point series can be entered in this column, or in the case of the center of mass, calculated. Click once to edit it. Note that only you can change the masses of located video points or designated points. The VideoPoint software automatically calculates the mass for a center of mass point series that is equal to the sum of the masses of the video points used in the center of mass calculation. Series Type This selection displays the type of the series such as video point, center of mass, etc. Scale Once the movie has been scaled by choosing Movie->Scale Movie, this area displays information about the points used for scaling. Movie Field This field displays the movie that is associated with the active coordinate systems. If the movie name is preceded with FILE: this means that the movie window is closed. Re-open it by choosing View->Movie. The Coordinate System Window can be saved without a movie for use with a set of movies. Details are included in section 4.2.

33 Video Point Manual Page 20 Icons on the Coordinate System Window There is always an icon representing a coordinate system at the left of the coordinate system header. There are three types of icons: Cartesian, Polar, and the Video Coordinate System icon. Cartesian Coordinate System This Cartesian icon specifies that points associated with coordinate system report their location as (x, y) displacements from the origin. To change to a polar coordinate system, double click on the icon in the coordinate system header. Polar Coordinate System This polar icon specifies that points associated with this coordinate system report their data as (r, θ) displacements from the origin. Double Click on the icon in the coordinate system header to change to a Cartesian coordinate system. Video Coordinate System This icon looks like a video frame. It represents the video coordinate system in which all data are reported relative to the bottom left of the movie window. Table Window Figure 3-8: The Table Window showing the Cartesian coordinate data for the point series named ball #1 for each frame. The time reported for each frame is the number of seconds since the first frame the movie was recorded. The table window displays the data for all the video point series (i.e., objects or features on the movie) whose locations and/or calculations change over time. The window can be accessed by clicking on the table icon in the toolbar or by choosing View->Data Table. The main purpose of this window is to allow you to examine the data and/or copy all or part of the data to the clipboard for use in another application such as a spreadsheet.!selecting Data versus Selecting Point Series

34 Video Point Manual Page 21 Note that selecting data on the table window does not automatically select the named point series on the Coordinate System Window or movie. Locating the Movie Frame Corresponding to Table Data Double clicking on a cell in the data table will advance the movie to the appropriate frame and select the corresponding point in that cell's series. Select All Region Clicking in the box to the left of the time header [t] will select all of the data in the table window. Selec t Time Row Clicking on a specific time value will select all the data for that time. Select Column Clicking on any of the [x] and [y] column headers will select the entire column. Graph Window Figure 3-9: A Graph Window showing a plot of the vertical position of Point s1 as a function of the time at which each frame was recorded. The Graph Window can be opened by clicking on the Graph icon in the tool bar or by choosing View->New Graph. This window displays a graph of the data chosen in the graph setup dialog box. Although you cannot add or remove items from existing graphs, creating new graphs is a simple process. You can also attempt to find an equation that serves as a model for the data. See section 2.2 for details. Locating the Movie Frame Corresponding to a Graph Point Click on the center of any point on the graph; this will select the point on the correct frame of the movie. You can then either move the corresponding point in the Movie Window by dragging it around or by using the nudge button on the toolbar. Changing a Graph Title

35 Video Point Manual Page 22 Click on the title to change it. Note that once you change the title, it will not be updated if you do anything like changing the units of the graphed point. Changing Vertical and Horizontal Axes Scales To change an axis scale click on either axis to change the range of the axis, and this dialog will appear. You can set whether or not the axis automatically scales with new data by checking the Auto Scale box. Figure 3-10: The Graph Scale Dialog Box. The scale of each axis can be set by the user. Click on any of these values to change the min./max. values for an axis. Note that doing so automatically turns auto-scaling off for that axis Edit Series Dialog Boxes Common Characteristics of Edit Series Dialogs The edit series dialog boxes allow you to change the characteristics of each type of item. Each item has its own edit dialog box; the section below describes how to use each type of dialog box. There are certain controls which are on all edit dialog boxes. These are listed first. Name Enter the name of the video point series in this area. The name can be up to 20 characters in length. Marker Click on the example marker to change the marker's color, size, or shape. Marker Visible Toggles the visibility of the marker on the movie. Even if the marker is designated as invisible, the video point can still be located. Leave Trails Toggles the visibility of the trails of the marker. If trails are visible, the markers of the entire video point series will be displayed on each frame.

36 Video Point Manual Page 23 OK Accepts the changes and closes the dialog box. Cancel Closes the dialog box without accepting the changes. The Edit Point Series Dialog The Edit Point Series Dialog Box can be opened by clicking on the series you wish to edit then clicking on the edit icon in the tool bar or by choosing Edit-> Edit Selected Series. Figure 3-11: The Edit Point Series Dialog Box. It can be used to assign a name, marker, mass, and coordinate system to a point series. The point series can also be designated as an origin. Mass Enter the mass of the feature represented by the video point series in the mass box. Entering a mass is important only if the video point series will be used as part of a center of mass calculation. Otherwise, you can leave it at 1 gram. Origin Select the origin name of the coordinate system to which you want data from the video point series transferred. This does the same thing as dragging the name of the point series in the Coordinate System Window onto a different coordinate system.

37 Video Point Manual Page 24 Coordinates Choose between Polar and Cartesian coordinate systems. If the video point series is in a Cartesian coordinate system, it will report its location to its origin as x and y displacements. If in polar coordinates, the video point position coordinates will be reported as (r, θ). The polar coordinates is extremely useful when looking at pendulum motion and rotating objects. Data Type You can choose three data types: Frame-by-Frame, Fixed, and Semi-Fixed. Frame-by-Frame is the normal data type. The Frame-by-frame feature needs to be located on each frame. You should choose Fixed as the data type if you want the feature to be in the same location throughout the entire movie. Moving a fixed feature on one frame moves it on all frames. Origin 1 is, by default, a fixed video point. Most of the video points that you designate as origins are Fixed. A Semi-Fixed origin is a video point that, once selected, will be fixed at the same location in the Movie Window until moved on a later frame. The point will be fixed at this new location unless moved at a later time. It does not move the locations recorded for the earlier frames. This feature is useful when the camera used to make the movie is fixed for awhile and then moves. Units Units for length can be in meters, centimeters or millimeters. Angle units can be either degrees or radians. Angle Range Angles (reported only if the video point series is associated with a polar coordinate system) can either range from -π to π (useful for pendulums), 0-2π, or -INF to INF. The [-INF,0,INF] range is useful for analyzing things that loop around themselves. Is an Origin Checking the Is an Origin box designates the video point series as a series of origins. This creates a new coordinate system on the Coordinate System Window. Two extra options appear; these are described in the section on the Origin Dialog that follows. If the Is an Origin box is already checked then unchecking it by clicking on it will remove the origin designation for the point series. Other point series associated with the coordinate system and origin you just removed will be reassigned to the Video Origin coordinate system. The Origin Dialog The origin dialog box is actually a point series dialog box with provisions for setting the scale and angle of the x-axis associated coordinate system. The dialog box can be located by checking the "Is An Origin" box at the bottom of the Edit Point Dialog box.

38 Video Point Manual Page 25 Figure 3-12: The Origin Dialog Box. It can be used to assign a name, marker, mass, and coordinate system to a point series. The point series can also be designated as an origin. Rotate (deg) This is the amount that the coordinate system is rotated relative to the horizontal. The angle is always relative to the horizontal and not relative to any other rotated coordinate system. Scale Item Choose the scale item that you want to use to scale the coordinate system that is defined by this origin. This is equivalent to dragging the scale item onto the coordinate system header. Unchecking the Is an Origin Box If you no longer want a point series to define the location of the origin on each frame of the movie, you can remove the origin by clicking on the Is an Origin box. The point series will no longer be designated as a series of origins. Any other point series associated with the coordinate system and origin you just removed will be reassigned to the coordinate system that the original point series is associated with. The Calculated Items Dialog Calculations can be performed by the VideoPoint software which are based on the location of two or more video points. Each of these calculated items is described in depth in the How Do I? chapter. Distance calculations will be in meters, or centimeters, or millimeters. Distances will be reported in pixels unless the active coordinate system has been scaled. Figure 3-13: A typical Calculated Items Dialog Box consisting of list of Available Points for the calculation.

39 Video Point Manual Page 26 Distance: Scale: The distance between two video points. Ratio of a known distance in pixels between two features or objects in the Movie Window and the known distance in center. Center of Mass: Calculated center of mass of a set of video points on each frame. To use this feature you must assign a mass to each video point series included in the calculations. based Angle: the vertex. Angles are marked on the movie window for a frame and calculated on the location of three video points. One of these points must chosen as Designated Point: Point at a location specified by relative distances from two video points. Designated points are useful for marking the center of mass of a human body segment that has a non-uniform mass distribution. Each calculated item s edit dialog box has a list of available video point series and a list of included video point series. The included video point series are used in the calculations; the available video point series are the remainder of valid video points (or video point-type items). Most of the calculated item dialog boxes have a similar format. Available Point Series List This list contains all of the point series or point-type series that can be included in the determination of the points in a calculated series. All point series and point-type series are shown (i.e., you can make a center of mass series by including two different center of mass series) in this list. Once a point series is included, it is moved from this list into the Included Point Series list. Included Point Series List This list contains all of the point series that you have chosen from the Available Point Series List to use in the calculation. To the right of the title "Included Points" there is a number or an N located in brackets. This number corresponds to the maximum number of point series you are allowed to use for the calculation. For example, if you are doing a designated point calculation you may add only two point series to this list. On the other hand, when (N) appears as in a Center of Mass calculation, you are allowed to add as many point series as desired to the Included Point Series List. Add >> This button takes the collection of point series selected in the Available Points List and moves them into the Included Point Series List. If the number of point series in the Included List is greater than the maximum number, this operation fails. << Remove Takes the collection of point series that are selected in the Included Points Series List and returns them to the Available Points Series List. Point Series Info Opens the edit dialog box for the last point series selected in either list. This is useful if you want to change the name or the mass of an included point series.

40 Video Point Manual Page 27 New Point Series This button will allow you to create a new point series and include it in the list. If the included list already has the maximum number of point series, this operation fails. The Edit Calculated Series Dialogs Distance Dialog A distance series consists of data for the distance between two specified video points for each frame of the movie. To create a distance series choose Create->Distance. A list of previously defined point or point-type series will appear in the Available Points box. Click on the point series you want included in the distance calculation and then click on the Add>> button. Figure 3-14: A Distance SeriesDialog Box. The user can select any two point series so that the distance between the two points on each frame can be calculated. Center of Mass Dialog You can assign masses to each named data point series and designate that the center of mass be calculated for a set of point series. For example, if you have entered data for the relative mass of each body segment for a college-age woman, then the center of mass of a ballerina can be determined automatically on a frame-by-frame basis as you locate the body segments on each frame. This feature allows you to study the floating illusion in the grand jeté in ballet or hang-time in the performance of a slam dunk as well as the path of the center of mass in a collision of many objects.

41 Video Point Manual Page 28 Figure 3-15: Analysis of a dancer doing a grand jeté. Each part of the body is assigned a relative mass; a center of mass of the chosen objects or features is calculated by VideoPoint. Note that the graph on the left shows the "floating illusion" of the dancer. The head rises and "floats" relative to the fixed origin. The center of mass, however, obeys the laws of physics and follows a parabola. How to Create a Center of Mass Calculation To create a series of center of mass points choose Create->Center of Mass. The center of mass dialog box will appear. A list of previously defined point series will appear in the Available Points box. Click on the point series you want included in the center of mass calculation and then click on the Add>> button. You must, of course, assign masses to each of the point series so that the center of mass points can be calculated by VideoPoint.

42 Video Point Manual Page 29 Figure 3-16: The Center of Mass Dialog Box. The user can select any group of video point series to be included in center of mass calculations. The Edit Point Properties button allows you to edit the name, marker, etc. of the Center of Mass point series as if it was a video point series. You can set things like the coordinate system and angle range; in this dialog box. See the Edit Point Series dialog box for more information. Scale Dialog What Scaling Is VideoPoint can calculate a scale factor if you locate the ends of an extended object of known length or the distance between a pair of objects in a movie frame. Once a scale factor is determined, coordinate data can be graphed and recorded in a data table in real units rather than the native screen units or pixels. For example, to obtain data needed to determine the free fall acceleration in m/s 2 of a small ball that is being tossed, you can use the known height of the person tossing the ball to determine the scale factor.

43 Video Point Manual Page 30 Figure 3-17: Situation before scaling. Note that all the units on the graphs and in the data table are in pixels. In most cases, you will create a scale using the Movie->Scale Movie menu command, and following the instructions that popup. However, you can also create a scale that uses two existing video points for its ends. This is useful when you have a zooming camera (see the The Camera Zooms in the What If chapter). Choose Create->Scale and the following dialog will appear. A list of previously defined point series will appear in the Available Points box. Click on the point series you want included in the scale calculation and then click on the Add>> button.

44 Video Point Manual Page 31 Figure 3-18: The Scale SeriesDialog Box. The user can select any two video point series to be the end points used in scale factor calculations. Length This is the length and units of the object or feature in the movie that you are using to create the scale.

45 Video Point Manual Page 32 Figure 3-19: Situation after scaling. In the scaling process, the user has selected the ends of the horizontal meter stick (Scale A and Scale B).and has also specified that its actual length is 1.00m. The program then automatically adjusts the units and values on the graph and in the data table. Also the scale factor is now displayed in the header of the coordinate system it is associated with. Designated Point Dialog In order to analyze certain types of movies, it is helpful to be able to point on a feature that is a known distance from two other points. For example, in the analysis of body motions in sports and dance, the motion of the joints and the center of mass of each limb is often displayed in an animated format. The designated point and point connection features of VideoPoint allow you to perform human motion analyses easily. You can define designated points relative to any two other points. For example, suppose we want to look at the relative motion of the finger tips, wrist, elbow, and shoulder of a tennis player during a serve. You can connect the finger tips to the wrist, the wrist to the elbow and so on to create an animation of the arm action during a serve. You can define a designated point by opening the designated point dialog box and entering the specifications for your designated point in it. (See the next section for instructions.) Figure 3-20: Arm Swing. Points are taken at each joint; lines are shown connecting the joints. Specified designated points that define the locations of the centers of mass between each pair of joints set the location of the point a relative distance from one joint to another. The Designated Point Dialog Designated Points are most often used when analyzing human body motions. The center of mass of a calf muscle, for example, may be 60% of the way from the ankle to the knee. A designated point, called Calf would be setup to have the mass of the limb located at 60% of the way from the video point Ankle to the video point Knee. The designated point dialog box can be opened by choosing Create->Designate Point or Edit- > Designate Point. A list of previously defined point series will appear in the Available Points box. Click on the point series you want included in the Designated Point calculation and then click on the Add>> button. A designated point has a relative displacement along the line connecting two video points as well as a relative displacement perpendicular to the line between the two video points. Often, the

46 Video Point Manual Page 33 perpendicular displacement is zero (0), and it simply lies a certain percentage of the way along the line from one video point to another. Figure 3-21: The Designated Point Series Dialog Box. The user can select any two video point series to be included in designated point calculations. Points (2) This popup menu determines which end of the line (A or B) that will receive the point that is added from the available list. Note that adding a point WILL remove another point at that location. % along AB Percentage of the distance between A and B that the point will be located along the line from A to B. Values greater than 100% place the point beyond B. Negative values position the point beyond A. % perp AB Percentage of the distance between A and B tha t the point will be displaced perpendicular to the line. Positive and negative % values will be allowed. Drawing Figure 3-22: An enlargement of the drawing the designated point series dialog box. This drawing shows a designated point that is 50% of the way from A to B.

47 Video Point Manual Page 34 The drawing gives a rough idea of where the designated point will be located relative to the line between A and B. However, large percentage values may locate the point off the drawing and may not be shown. Clicking on the drawing will either select A or B (same as the Select Point popup) or will enter values into the % perp and % along fields. Angle Dialog The angle reports the angle between the lines connecting three independent video points one of which is chosen as the vertex. Video points representing points A, B, and the vertex should be added from the available list. The Angle calculation dialog box can be located by choosing Create->Angle. A list of previously defined point series will appear in the Available Points box. Click on the point series you want included in the angle calculation and then click on the Add>> button. Figure 3-23: The Angle Series Dialog box which allows users to determine the angle between two point series and a vertex. Points (3) This popup menu determines which end of the angle (A, B, or vertex) will receive the point that is added from the available list. Note that adding a point WILL remove another point at that location and return it to the available list. The drawing shows how the angle will be reported. Note that the order in which video points are selected for angle calculations is very important. Clone Point Series Dialog To report data for a video point or point-type series in two coordinate systems simultaneously, you need to clone the first series. The Clone Point Series dialog box can be located by choosing Create->Clone. To clone a series, select it from the list and click on OK. Once the series is cloned, you can edit it like any other series.

48 Video Point Manual Page 35 Figure 3-24: The Clone Point Series Dialog Box allows users to create a clone of a point series to associate with a different coordinate system. Count Objects of Interest The count item allows you to record the number of objects of interest you locate on each frame. The Count dialog box can be located by choosing Create->Count. The only options on the count dialog box are the name, marker, marker visibility and leave trails. Figure 3-25: The Count Objects Dialog Box which allows users to keep count of the number of objects or features of interest on each frame in a movie Utility Dialog Boxes Marker Dialog You can select the size, shape and color of the marker to be placed on the screen corresponding to each point in a series. These markers can be made quite large for lecture demonstrations. They can also be horizontal or vertical lines or vectors referred to the location of the object on the previous screen.

49 Video Point Manual Page 36 Figure 3-26: Three body parts with three different markers and three different names. Names can be typed directly into the "Coordinate System" window. Markers can be selected using a dialog box. If the markers for the points you have located are turned on, a trail of them will appear on the active movie frame. But if leaving the trails on clutters up the screen, they can be turned off with a click of the mouse. For example, in following the paths of three odd shaped objects on an air table, it is distracting to advance through the frames and accumulate dozens of screen markers while locating the features or objects of interest on each frame (see figure 1-3). However, once all the data points are chosen, it is interesting to see the path of each object as collisions take place. If you are following the progress of a projectile, it is informative to use a vertical line as a marker and select leave trails. If trails are left on as you make selections, you can see a series of equally spaced vertical lines emerge as you locate the projectile on each frame. Figure 1-4 above shows a frame of a projectile with trails off and trails turned on. F igure 3-27: Left image of this projectile launch shows a video point on the active frame with a line type of marker on it. Right image is same frame with trails turned on so that the constant horizontal motion of the projectile is accentuated. To open the Marker dialog box you can either click on the marker icon in the toolbar or c hoose Edit-> Marker. The marker dialog box lets you choose from a bunch of different markers. A nice feature of the marker dialog box is the Apply button. This allows you to view the marker change immediately on the movie (assuming that the marker is visible!) without closing the dialog box.

50 Video Point Manual Page 37 Figure 3-28: The Marker Chooser Dialog Box which allows users change the size color, shape and type of marker displayed on the screen for each video point in a series. How to Choose and Apply a Marker Type The markers that are used to show locations on the movie frames can be chosen to accentuate particular features of a motion. You can choose from a wide array of shapes, sizes, colors and marker types. In order to change a marker, you must click on a new marker in the selector box located in the upper right corner of the Marker Chooser Dialog Box. The example box labeled i.e. will display the new marker. A list of the marker types follows. Point Series (Point): Point Series markers are discrete marks centered on the locations on each movie frame that belong to a given point series. Lines:.i.axis:markers; If a lines marker is chosen then lines will be drawn that extend from the edges of the movie window through the point. Vertical and/or horizontal lines can be chosen. When trails are turned on these lines can be used to emphasize the spacing between points for motions involving constant velocity or constant acceleration.

51 Video Point Manual Page 38 Change: A change marker consists of a line segment that displays the change in position from a point on the active movie frame to a corresponding point on the next movie frame. When you are stepping through a movie taking data the change marker will be a little cross (since the location of the object or feature of interest has not yet been marked on the next frame). Once you finish locating the video points on each frame, the series of change markers can be displayed whenever trails are turned on. Vector: Vectors represent the displacement vectors. These vectors point from the origin of the coordinate system to the location of the point associated with the origin. Marker Color: To pick another color for a marker you should click on one of the color squares in the Marker Chooser Dialog Box. These squares are located in the lower left corner of the Dialog Box. Scale Movie Dialog This dialog box appears when you click on the scale icon in the Toolbar or choose Create- >Scale or Movie->Scale Movie. Unless the camera zooms during the movie, you can leave the scale type as "fixed" and just enter the known length of the object in the movie. If the camera zooms, see the section The Camera Zoom in the What If chapter. Figure 3-29: The Scale Movie Dialog Box which allows users to enter the length of an extended object (or alternatively the known distance between two features) on a movie frame. The scale is associated with a coordinate system (named for its origin).

52 Video Point Manual Page 39 Origin This option allows you to choose which coordinate system that you want to scale by selecting the corresponding origin. See the note about scaling multiple coordinate systems before creating a different scale for each coordinate system.!scaling Multiple Coordinate Systems If you have multiple coordinate systems that are in the same plane (equidistant from the camera), you should share one scale factor across some or all of the coordinate systems. The easiest way to do this is to first scale one of the coordinate systems, then, on the Coordinate Systems Window, drag that scale s row onto each of the coordinate systems that will share the scale. Graph Dialog You can create graphs of the (x, y, or t) or (r, θ, or t) coordinates of point series as a function of time or of any of the coordinates recorded for other point series you have created. The coordinate data are determined relative to a default coordinate system or any other 2D system you choose to define. Suppose you choose to view graphs of x vs. t and y vs. t describing the path of a ball undergoing projectile motion. These graphs can be selected before, during or after the locations of the ball are marked on each screen. Any graphs that are pre-selected before the data points are placed on each frame will unfold as the data are being selected. Figure 3-30: x vs. time and y vs. time shown for the ball toss. How to Create a Graph You can open the graph dialog box by clicking of the graph icon in the toolbar or View- allows you >New Graph, or Ctrl-G for Windows or Command-G for MAC. The graph dialog box to create a plot of any number of point series values relative to a set of values from a single series.

53 Video Point Manual Page 40 Figure 3-31: The Graph Setup Dialog Box which allows users to choose the series to be graphed on the Horizontal Axis and the series or set of series to be graphed on the Vertical axis. Horizontal Axis Select one series from this list to represent the horizontal axis. Vertical Axis Select one or more series from this list to be plotted against the horizontal values. Creates a new graph. If no horizontal series or no vertical series is chosen, no graph is drawn. Model Dialog Plot You can open the Model Equation Dialog by bringing the Graph Window to the front and choosing Graph-> Add/EditModel. The model dialog lets you chose some equations that can be used to model your data. First choose the equation that you think will model your plot the best. Next, change the constants and hit Apply to see your results. Continue changing the constants until you are satisfied with your model. The x= and y= lines display which series are being used in the equations. If you have more than one series plotted on the vertical axis, it will take the first one on the list and use it as the y value. Figure 3-32: The Modeling Dialog Box which allows users to attempt to choose a type of equation and its constants such that the graph of the equation matches a graph of data.

54 Video Point Manual Page 41 Equation Use this popup menu to choose the a type of equation that might represent the data. A:, B:, C: and D: These boxes contain the values of the constants A, B, C and D to be placed in the equation. Apply Use the Apply button to view your model on the graph without closing the model equation dialog box. Frame Rate Dialog Movie taken with a high speed or time lapse camera may have unusual frame rates not properly recorded in the movie. You can use the Frame Rate dialog box to change the default frame rate of the movie. You can locate the dialog box by choosing Movie->Select Frame Rate. Changing this is not a good idea unless you know that the time code on the movie is incorrect. For example, to enter the frame rate for a time-lapse movie recorded at 1 frame per 100 seconds, you should enter 0.01 in the dialog box. Figure 3-33: The Change Frame Rate Dialog Box allows users to adjust the times reported for each frame on movies. Choose the frame rate that you want from the popup menu. If the rate that you want is not listed, choose Other and type the new value into the box. Choosing Default will let VideoPoint read the time from the movie file. Movie Step Size Dialog If the movie has more frames per second than you want to analyze, you may want to set a step size to analyze fewer frames in each second of the movie. Choose either one of the default step sizes from the popup menu or choose Other and type in your own. To open this dialog box choose Movie->Set Step Size.

55 Video Point Manual Page 42 Figure 3-34: The Movie Step Size Dialog Box allows users to skip frames on a regular basis when the analysis of all the frames in a movie would be unnecessary and tedious. Coordinate System Dialog Double clicking on the Coordinate System icon,, or in the Coordinate System Window calls up a coordinate systems dialog box. This allows you to change all the video point series and calculated items relative to this system from cartesian to polar coordinate or vice versa. Any series that are later made relative to this system will be changed to the correct coordinates. Figure 3-35: The Coordinate System Dialog Box allows users to change the current coordinate system to either a Cartesian or a polar system. Graph Scale Dialog You can open this dialog box by clicking on either the horizontal or vertical axis on the graph. Figure 3-36: The Graph Scale Dialog Box. The scale of each axis can be set by the user. Use this dialog box to change the scale of either axis of the graph. Enter minimum and maximum values for the scale or choose Auto Scale to have VideoPoint choose them for you. Click Apply to see how these changes affect your graph (without closing the dialog box). You can also rescale your graph directly on either graph axis by clicking on the numbers corresponding to maximum and minimum values and entering new maximum and minimum values from the keyboard. In addition, there is a zoom graph feature. Holding down the Ctrl key, depressing the mouse button and dragging the mouse diagonally across the region of the graph you want to zoom in on will enlarge that region. Ctrl-double-clicking will autoscale both axes of the graph. Change Scale Dialog Change Scale can be opened by choosing Options->Change Scale. Use this dialog box to change the characteristics of the scale item(s) in your Coordinate System Window. Primarily, this is an easy way to adjust the actual length in meters, centimeters or millimeters of the object or features

56 Video Point Manual Page 43 used as the scale. You can also change the scale type so that scaling can be done frame-by-frame. This is really only important when either the camera zooms or moves towards/away from the scene of interest. Both of these actions cause the ratio of pixels to meters, centimeters, or millimeters to change on a frame-by-frame basis. See The Camera Zoom in the What If chapter for information on how to use Frame-by-Frame scaling. Figure 3-37: The Change Scale Dialog Box which allows users to change the information about the scale for a movie. Clear All... Dialog Clear All... can be opened by choosing Edit->Clear All. Use this dialog box to clear the location of frame-by-frame, semi-fixed, or fixed point series in the entire movie. You can choose to not clear the origins and the ends of the scales for the movie by checking or unchecking Origins or Scale Ends. Figure 3-38: Clear all Choices Dialog Box. select the points that you want to clear Menus The Apple Menu (MAC Only) The menu item "About VideoPoint" in the upper left of every Macintosh computer opens a brief summary of information about the VideoPoint Software. The File Menu

57 Video Point Manual Page 44 Figure 3-39: The File Menu New Startup... Begins the setup process of choosing a movie, saved file or blank coordinate system for analysis. Open Movie... Chooses a movie for analysis. Open Saved Data... Opens a saved Video Point file. Close Window Closes the active window. Save As... Saves the current Coordinate System Window and associated windows to a new data file. Save Creates a new data file if it hasn't been saved before, otherwise it updates the current file. Export Data... Dumps all the data that has been taken to a text file. All data including mass and item type are sent to this file. It also contains the locations of fixed video points. Page Setup

58 Video Point Manual Page 45 Opens the standard Page Setup dialog box. Print Window Prints the active window to a file with some header information. Quit Quits VideoPoint. The Edit Menu Figure 3-40: The Edit Menu Edit Selected Series... Opens the Edit Dialog box for the selected series. These dialog boxes will be different for different types or series (point, center of mass, distance, etc.). Change Marker... Opens the Marker Chooser Dialog box for the selected series. The marker that indicates the location can be changed. Leave/Hide Trails Toggles trails on and off for all selected video point series. Hide/Show Selection Toggles the visibility of all selected series.

59 Video Point Manual Page 46 Show All Makes all series visible. Clear Selection on Frame Clears the data for the selected series on the current frame. However, the series name and characteristics still exist. Clear Selection All Frames Clears the data for the selected series for all the frames in the movie. Clear Frame other Clears th e data for the current frame from all items. This is useful if you want to retake all the data on a frame. Clear All... Clears the data for all frames from all items. Copy (Movie/Data/Window) Copies t he active window to the clipboard. The Table Window is copied as text. The other windows are copied as bitmaps. De lete Selection Deletes any video point series or selected item that is highlighted on the screen. The series and all its data are entirely removed from the coordinate systems header. Select All Selec ts a ll items in the open window allowing you to copy or delete all of the items. The Options Menu

60 Video Point Manual Page 47 Figure 3-41: The Options Menu Auto Add Points If Auto Add Points is turned on, each time you click on a movie frame a new video point series will be created. You will prompted for a series name and other information. Auto Point Advance If Auto Point Advance is checked, after a video point is located on a movie frame, VideoPoint will set you up to locate the next video point from the next series that should be located on the frame. If all the video points have already been located, nothing is selected. Auto Frame Advance If Auto Advance Frame is on, the movie will advance one frame as soon as all the video points from all of the video point series on a movie frame have been located. If Auto Point Advance is off, Auto Frame Advance will advance the movie when the selected video point is located. Make Point Origin If a video point series is selected it will be transformed into an origin series. This option allows you to record data of one point series relative to another video point series. Thus, you can record coordinate data of the motion of one object or feature in a movie relative to the motion of another object or feature. Transform Origin If the object on the movie that you are using for an origin should happen to move off the screen, you can transform the origin to some other object that is on the movie afterwards. To transform an origin, go back to the last frame in which the object was visible and find another object or feature on that frame that will become the new origin. See Transform an Origin in the How do I? chapter. Set Default Origin (Coordinate System) Sets a coordinate system and its associated origin to the default. It is usually a good idea to leave the original coordinate system, initially named "Origin 1", as the default system. Change Scale... This brings up a dialog box that lets you change the length of any scale that is present on the movie. Remove Movie... The movie will be closed and all data associated with it will be cleared. However, any coordinate systems that have been created will be retained, although the data associated with each of them such as angle of rotation and origin locations will be cleared. Also, the basic properties of any point series that have been created and the properties they have been given such as mass, is an origin, association with a coordinate system and so on will be retained. The Remove Movie is a valuable feature in the analysis of complex systems that recur such as those used in the analysis of human motion. Point series and their relative masses for each body segment for a typical male or female athlete can be retained from movie to movie.

61 Video Point Manual Page 48 Switch Movie... Switch movie is designed to let you easily analyze a series of movies that have been taken with the same fixed camera. If, for example, you took a series of movies of people measuring their vertical leap with the same camera at the same location, you could set up the scale and origin for the first movie, take and save data, then switch to the next movie! since the scale and origin will be kept, all you have to do is take data. When you switch movies, the movie will be closed and data associated with it will be cleared and the user will be returned to the finder to choose a new movie. However, fixed data and information about origins, coordinate systems and scale factors will be retained. The Create Menu Each menu choice creates a new series and opens the respective dialog box. See Sections 3.2 and 3.3 of Chapter 3 for more information on how to use the edit dialog box for each series. Figure 3-42: The Create Menu Point Creates a new video point series for the selected feature or object. Origin Creates a new coordinate system and associated origin series. By default, this origin series is a frame-by-frame origin. You can easily change the series it to a fixed or semi-fixed type of origin. Center of Mass Calculates a video point-type series in which each calculated point is at the center of mass of the included video points on a frame. Distance A distance calculation reports the distance between specified pairs of video points.

62 Video Point Manual Page 49 Scale Creates a scale factor using two existing objects or features that are a known distance apart. The scale factor is the ratio of the frame pixels between two scale points you have located (such as Scale A and Scale B) and the known distance in meters, centimeter, or millimeters between these scale points. Normally, you should use Movie->Scale Movie to scale a movie unless you want to use two existing video point series to create the scale. Clone Creates a video point series identical to that of the selected video point series. Cloning a video point series allows you to determine positions for a video point series relative to two different coordinate systems. Angle Reports the angle between the lines connecting two video points on a frame to a third video point which is designated as a vertex. Designated Point Creates a designated point series. Each designated point is located relative to the locations of two other video points on each frame. A designated point can have a relative displacement along the line connecting the two points as well as a relative displacement perpendicular to the line between two points. Count Keeps count of the number of objects or features of interest in each movie frame. The Movie Menu Figure 3-43: The Movie Menu Rewind Resets the movie to its first frame. Scale Movie Starts the scaling process. Set Step Size

63 Video Point Manual Page 50 Opens the movie step size dialog box, allowing you to analyze fewer frames. Select Frame Rate Overrides the default frame rate of the movie. Use this ONLY if you know the time code of the movie differs form the actual times at which the frames of the movie were recorded. Half Size This changes the size of the movie box relative to the default size that is stored in the digital file. (Normally we suggest that movies be digitized in a 320 X 240 pixel size.) Normal Size This sets the size of the movie back to the default size that is stored in the digital video file. (Normally we suggest that movies be digitized in a 320 X 240 pixel size.) Double Size video This changes the size of the movie box relative to the default size that is stored in the digital video file. (Normally we suggest that movies be digitized in a 320 X 240 pixel size.) Fill Screen This changes the size of the movie box to the maximum size that allows you to still use the movie controllers. Keep Aspect Ratio If checked, this retains the aspect ratio of the movie when resizing. Otherwise, the movie can be distorted, though the data will still be correct. Play All Frames If "Play All Frames" is checked, VideoPoint will play every frame of the movie at a constant speed. Otherwise, it will attempt to play the movie at its original frame rate (which in some cases, will skip frames). Show Frame Numbers Shows the frame number at the top right hand corner of the movie window. The Window Menu Figure 3-44: The Window Menu Tile

64 Video Point Manual Page 51 This command rearranges the screen so that all of the windows can be seen. Cascade This command rearranges the screen so that the windows lie one on top of each other. Hide Window This command hides the current window. Close All This command closes all open windows. Coordinate Systems This command brings the Coordinate Systems Window to the front. Current Movie Window This command brings the movie window to the front. If the movie window has been closed, it opens it. Table Window This command brings the table window to the front. If the table window has been closed, it opens it.

65 Video Point Manual Page 52 The View Menu Whenever a window is selected from the View window, it is the one associated with the currently active window. For example, if you have two data tables containing data from two different movies, selecting View->Movie will bring the movie which matches the active data table to the top. Figure 3-45: The View Menu Movie The Movie command makes the appropriate movie window active and brings it to the front. If the movie window is closed, VideoPoint opens it. Coordinate Systems This command brings the current Coordinate Systems Window to the front. Data Table This command opens a data table associated with the movie window or coordinate systems window that is currently active. It reports all the data that changes over time. New Graph... This command opens a dialog box that lets you plot data. See "Graph Dialog Box" in section 3.3 of this chapter. Toggle Background. -MAC This command toggles the background window that covers up the Finder and other open programs. Graph Menu The GraphMenu can only be located if the Graph Window is the top window. Figure 3-46: The Graph Menu Add/Edit Model This adds a new model or allow you to edit the current model for the active Graph Window. Each graph can only have one model (see section 2.2 on Model Dialog Boxes for details).

66 Video Point Manual Page 53 Visible Legend If this is checked, a legend will appear on the graph. By default, the legend only appears on new graphs when more than one data series is to be plotted on the same graph. Moveable Legend If the legend is visible, checking this menu choice gives you the choice of having the legend fixed in the right side of the graph or having the ability to drag the legend around the graph The Toolbar The toolbar buttons are as follows: Selects the next video point that can be located on the current frame. Allows user to select and move an existing video point marker. Toggles context sensitive help on or off (similar to Macintosh balloon help). Selects the previous video point series listed in the Coordinate System Window. Selects the next video point series listed in the Coordinate System Window. Allows user to scale the active coordinate system. Hides/Shows the Coordinate System Window. Hides/Shows the Table Window. Allows user to create a graph. Allows user to change the size or shape of the selected marker. Toggles to display or hide the entire series of video points associated with a selected video point. Toggles Trails of the selected features Names a new video point series Allows user to edit a video point series Allows user to relocate the origin or orientation of a selected coordinate system. Nudges the selected video point 1 pixel in any direction; click on the appropriate arrow to nudge. MAC only. Toggles the background window off or on to hide screen objects that do not belong to VideoPoint.

67 Video Point Manual Page How Do I? This section answers some of the most common questions about using VideoPoint. Answers are organized into the headings listed here. 4.1 Get Help 4.2 Open and Save Files 4.3 Take Data 4.4 Select Items 4.5 Clear Data/Delete Series 4.6 Edit Series 4.7 Create Items 4.8 Modify or Move Calculated Items 4.9 Define Coordinate Systems 4.10 Take Short Cuts 4.11 View Movies 4.12 Display Data 4.1. Get Help Mac A Balloon-type help system is available on the Macintosh version of VideoPoint. To use it, click on the icon and move the cursor around the screen. To see a help balloon you should place the cursor on any VideoPoint element of interest on the monitor screen. Windows Choose Help->Context to get more information about the current window or Help->Contents for a general overview Open and Save Files Open a Movie Choose File->Open Movie... This will open a movie for analysis and create a new Coordinate System Window, or if the current Coordinate System Window has no movie associated with it (see Saving a File Without a Movie ), this will attach a movie to it. Open a Saved File Choose File->Open Saved Data... Open a New Setup Choose File->New Setup... This setup window allows you to choose between opening a new movie, opening a saved file or opening a blank Coordinate System Window. Save a File

68 Video Point Manual Page 55 Choose File->Save. This will save all the data and graphs. Save a File as a Different Name Choose File->Save As... Export Only the Data to a File Choose File->Export Data. This will save a tab-delimited text file that can be read by any spreadsheet or other math analysis package. Save a File Without the Movie First, choose Options->Remove Movie. This will remove the movie and clear all the data associated with the movie. It will, however, retain information about the coordinate system type and the associated point series properties such as mass, designation of series as an origin and so on. The Remove Movie is helpful in the analysis of complex systems that recur such as those used in the analysis of human motion. Point series and their relative masses for each body segment for a typical male or female athlete can be retained from movie to movie. You can then save this "Analysis Setup" as a data file Take Data Take Data by Locating Video Points You take data by locating features or objects of interest on the movie. The process consists of a) choosing a name for the video point series you want to locate (or using the default name already assigned), and b) clicking on the movie where you want the video point in the series on the active frame to be located. Note that calculated video points, such as the Center of Mass and Designated Points, are determined from the video points that you select to be included in the calculation. For example, if you had a calculated center of mass of two carts, Big Cart and Little Cart, the center of mass would be located for you once you have chosen the video point locations on a frame for both Big Cart and Little Cart. Move Video Points If a video point has already been located on a frame, but not in the correct location, you can select and move the video point by clicking on it and dragging it around in the movie window. If the point refuses to be moved around the screen, it is most likely a calculated series which you cannot move. Figure 4-1: Example of the Point Series cursor for locating each point and the arrow used to select a previously located video point to move it.

69 Video Point Manual Page Select Items Select a Video Point Series You can select a video point series by a) clicking on the name of the video point series in the C oordinate System Window, b) using the up- and down- arrows on the toolbar until the name of the selected video point series is shown in the bottom right of the movie window and is also highlighted in the Coordinate System Window, or c) if the video point has already been located on the active movie frame and its marker is visible, clicking once on the video point marker will select it. Once a video point is selected on a frame it will have a circle around it. Figure 4-2: A video point which has been selected. Select a Group of Video Points You can select more than one video point series at a time by holding the shift key and clicking on each video point series either in the movie window or on the series names listed in the Coordinate System Window. You can also drag a rectangle on the movie window the includes the markers for a cluster of video points on the movie frame that you want to select. However, you can only move one video point at a time. Select a Calculated Video Point Series You can select a calculated video point series by a) clicking on the video point series name in the Coordinate System Window, b) Using the up- and down- arrows on the toolbar until the video point series name is shown in the bottom right of the movie window and/or is highlighted in the Coordinate System Window. Select the Next Video Point that Needs to be Located You can select the next video point that you want to locate by clicking on the icon on the toolbar. If Auto Point Advance is on, VideoPoint will automatically select the next video point that needs data on that frame ONLY after you have located a different video point. If you have just moved a video point or have been editing some video points that have been located, you will need to click on the icon to continue taking data Clear Data/Delete Series Clear the Selected Video Point on a Frame Once a video point is selected, you can clear the video point by choosing Edit->Clear Selection on Frame. This will clear the data for all the selected series; however, the series will still remain in the Coordinate System Window and can be relocated on this frame.

70 Video Point Manual Page 57 Clear All the Data Choose Edit->Clear All. This opens the "Clear All" dialog. This dialog allows you to clear the data for all types of video point series for the entire movie. Clear the Point for All the Frames Choose Edit->Clear Selection All Frames. This will clear all the locations for all the selected video points for all the frames.! Clearing vs. Deleting Clearing data only removes the locations and (x, y, t) data associated with a video point series, but the video point series name and other characteristics given to it remain intact. Deleting data removes the locations and (x, y, t) data associated with a video point series along with the video point series itself. Delete a Series Delete a Located Video Point Series Select the located video point series that you want to delete. Choose Edit->Delete Selected. Delete a Calculated Point Series Select the calculated video point series and then choose Edit>Delete Selected. This will NOT delete video points that are used to calculate the series Edit Series! Edit Dialog Boxes Each type of series has its own edit dialog box. Some of the characteristics listed here do not apply to all types of series. See section 3.2 in Chapter 3 to learn more about each type of dialog box. Edit a Series Select the series that you wish to edit. To edit the characteristics, either a) choose Edit->Edit Selection...(Ctrl-E for Windows and Command-E for MAC), b) double-click on the left box on the video point s line in the Coordinate System Window, or c) if the video point has already been located on the current frame of the movie, you can double-click on the video point s marker on the movie. In any case, editing a series brings up the appropriate edit dialog box and you can change any of the characteristics of the series. Change the Marker of an Series

71 Video Point Manual Page 58 Select the series. Once selected, either click on the icon in the toolbaror choose Edit- >Marker. See the section Marker Dialog Box in the Functional Description chapter. Change the Name of a Series You can either change the name in the edit dialog box for the series or change the name directly on the Coordinate System Window by clicking once on the name. Change the Mass of a Series You can either change the mass assigned to a series in the Edit Dialog Box or directly on the Coordinate System Window. Show/Hide a Series Select the series. Clicking on the icon in the toolbar toggles the visibility of the series. You can also hide and show a series on the movie by checking and unchecking the V column on the Coordinate System Window. Visibility can also be set by checking the Is Visible box in the edit dialog box for the series. Turn a Series Trail On/Off Select the series and then click on the trails icon in the toolbar to toggle on the trail and hence the location markers for all the points in the series. You can also toggle the trail for selected series by clicking in the T column in the Coordinate System Window. Report Point Series Data in Polar Coordinates Any series can have its coordinates reported in polar (r, θ) format. This can be set in the series Edit Point dialog box in the Coord.Sys popup menu. Note that for calculated point series (such as the center of mass), you will need to click on the Edit As Point... button on the edit dialog box for the series. Change the Angle Range for a Series Sometimes, you will want to get angle data from either -π to π or from 0-2π. Also, if the object in the movie is spinning, you might want to get angles in the range from -INF to INF. In the series edit dialog box, select the range in the Angle Range popup.

72 Video Point Manual Page Create Items You can create and define characteristics for many types of items including video point series, coordinate systems ("origins") and center of mass series.! Create See Section 3.2 on Edit Dialog Boxes in Chapter 3 to learn how to use the edit dialog box for each type of item. Create a Video Point Series Choose Create->Point. This will create a new video point series and open the video point s edit dialog box. Another option, which is useful if you want to create a bunch of new video points, is to use the Auto Add Points feature. This adds a new video point every time you click on the movie until you turn Auto Add Points off. See "Auto Add Points" in the Menus section of the Functional Description chapter for more information. Create an Origin (Coordinate System) When you create a new origin, you are defining a coordinate system. After choosing Create- of the movie. >Origin you can give your new origin a name and specify its location on each frame Since a new coordinate system which carries the name of your origin has been created, you will see a header for this new system in the Coordinate System Window. You are free to change the characteristics such as the scale factor, orientation and so on of this new coordinate system. Create a Center of Mass Series When yo u choose Create->Center of Mass an edit center of mass dialog box will appear. You can use this dialog box to name the center of mass series you are creating and to choose a set of previously defined video point (or point-like) series to be included in the center of mass calculation. Create a Designated Point When you choose Create->Designated Point an edit designated dialog box will appear. You can name your designated point, choose the end video points to be included and enter the data needed to calculate coordinates for your designated point. Create an Angle Choose Create->Angle. Once the edit dialog box for the angle item opens, you can choose three video points that make up the ends and the vertex of an angle. Create a Count A count item lets you count the number of features or objects of interest on a frame. It marks where you click, but only reports the number of clicks on each frame. For example, you could, for example, count the number of blue air table pucks in a region to track entropy increases using a movie from the Princeton Collection such as PRU035.MOV. Or you might want to use two count items to analyze a time-lapse film of an area in a shopping mall and track the numbers of men and women present at different times of day. the

73 Video Point Manual Page 60 Choose Create->Count to create a count item. When the count item is selected, each successive click on the move window will add one to the count on the current frame. When you are finished counting objects on a frame you can use the movie controller bar to change to another frame and count objects on it. The number of objects or features counted on each frame will be displayed in the data table. Create a Scale (the easy way) Either click on the icon on the toolbar or choose Movie->Scale Movie. This will start the scaling process. See the entry entitled Scale Movie Dialog Box in Section 3.3 or Chapter 3 to see how to set the options on the dialog box. Create a Scale (the hard way) Choose Create->Scale. This opens a blank scale edit dialog box. You will need to include two video points that make up the scale ends. This is useful when the video points by which you scale the movie are also video points that you have already taken on the movie Modify or Move Calculated Items Add a Video Point Series to a Calculated Series Each calculated series is calculated from two or more video point series or other previously calculated series. In order to include a video point series in a calculated series, you need to: 1) open the edit dialog box for the calculated series, 2) select the video point series that you want to add from the available video points list, and 3) click on the Add >> button to add them to the list. Certain series can have a maximum number of video points that can be included. Add>> will not replace a video series. See the description of the dialog box for each series in Section 3.2 of Chapter 3. Figure 4-3: A typical calculated series dialog looks much like the Distance Series dialog shown above. In this case the user is selecting two point series, ball 1 and ball 2, in order to determine the distance between them on each frame.

74 Video Point Manual Page 61 Remove a Video Point Series from a Calculated Series To remove a video point series from a calculated series, you need to first open the edit dialog box for the series. Select the video point series that you want to remove in the included list and click on <<Remove. Move Calculated Points You can t move a calculated point directly by clicking on it and dragging. However you can move a calculated point indirectly by moving one or more of the included video points. By moving one of the included points, you will most likely move the calculated points. Locate Calculated Points You cannot locate calculated points directly by clicking on the screen. Instead you must locate the video points which are included in the calculated point Define Coordinate Systems A Coordinate System, when fully defined, has an origin which is located relative to the Video Origin, a scale factor that is used to determine locations of objects of interest in real units, a type Cartesian or polar, and an angle of rotation with respect to the native video coordinate system. Whenever you create an origin or designate an existing point series as an origin, you are actually defining a new coordinate system and a header for it will appear in the Coordinate System Window. Initially each new system is a Cartesian system with no scale factor associated with it and no angle of rotation. A header for your new system will appear in the Coordinate System Window. Once a new system is created, you can change its characteristics. Current information about scale factors and rotation angles for the Coordinate System will appear in its header. Data specifying the origin location will appear in the native Video Coordinate System (or whatever other coordinate system that origin is associated with. Coordinate System Origins Create a New Origin Choose Create->Origin. This will create a new video point that is designated as an origin and also create a new coordinate system for it in the Coordinate Systems Window. Alternately, select the point series that you want to become an origin series. To make this point an origin, you can a) click once on the O column in the Coordinate Systems Window of the selected point, b) choose Options-> Make Point Origin, or c) edit the point and check the Is an Origin box. Decide where to Locate an Origin If you want a stationary origin, choose an object or feature that does not move in the plane of the movie. Objects such as tables and doors make good origins. Note that if the camera moves, you will need to click on the location of the origin on each frame. See "The Camera Move" in the "What If" chapter if this is the case. Transform an Origin

75 Video Point Manual Page 62 If the object on the movie that you are using for an origin should happen to move off the screen, you can transform the origin to some other object that is on the movie afterwards. To transform an origin, go back to the last frame in which the object was visible then find another object on that frame that will become the new origin. Select the old origin, and then choose Options->Transform Origin. This will popup a small pink cross next to the original origin. Move this pink cross to the location of the new origin. From the next frame on, you will click on the location of the new origin. See Transforming Origins in the Advanced Features chapter. Set the Default Origin Whenever you create a new point series or calculated series it is automatically associated with the default coordinate system. Since you can change the name, origin location, type of coordinate system and so on of the default coordinate system, you will usually want to associate the video points and calculated series you create with it. However, there may be instances in which you want to define and associate several series with one of the other coordinate systems. Select the origin. Choose Options->Set Default Origin. It is usually a good idea to leave the original origin ( Origin 1 ) as the default origin. Remove an Origin If you no longer want a point series to define the location of the origin on each frame of the movie, you can remove the origin by clicking on the Is an Origin box. The point series will no longer be designated as a series of origins. Any other point series associated with the coordinate system and origin you just removed will be reassigned to the coordinate system that the original point series is associated with. Scale a Coordinate System In order to scale a Coordinate System, there has to be an object (i.e., a meter stick) of known length. If the camera does not zoom, the object needs to be in only one frame of the movie. When you make your own movies, be SURE to keep something like a meter stick in the frame of the movie. Whatever you choose for your known length it is IMPERATIVE that the object be in the same plane as the motion of interest. If the object is behind the motion, the scale factor (in pixels/meters) will be too small (since the length of the meter stick will appear to be too small on the movie). Create a New Scale If you want to create a scale, click on the icon in the toolbar or choose Create->Scale. Either action will start the scaling process. You will be asked to enter a scale length in a dialog box and click on the ends of the object of known length. Use a Scale with Another Coordinate System If you want to use a scale that has been already created on this movie with a different coordinate system, you can either a) drag the scale icon from its coordinate system onto the header of the new coordinate system that you want to scale. See the section entitled Scale Series Dialog in Section 3.2 of Chapter 3 for instructions on using a dialog box as another way to associate a scale with the point series in various coordinate systems.

76 Video Point Manual Page 63 Change a Scale Once both ends of a scale item have been located on a movie, the scale factor pixels/meter) can be changed in a few ways. You can either move the locations of the end video points (closer reduces the scale factor) or change the known length of the scale itself. Change the Length of a Scale Item If you entered the wrong length of the object in the movie that is used for scaling (i.e., it s a 2 meter stick and you entered 1 meter for the known length), choose Options->Change Scale.... Alternatively you can select the scale that you want to change in the Scale popup menu and then enter the new known length of the object or select the scale on the Coordinate System Window. Next you should choose Edit->Selected Series and change the number in the length field. Choose Polar or Cartesian Coordinates The icon on the coordinate system header indicates whether the coordinate system is Cartesian or polar. Double click on the system header to get a dialog box that lets you choose between Cartesian and polar coordinates. Rotate a Coordinate System There are several cases in which the it is advantageous to have an x-axis that is not horizontal. For instance, motion on an incline can be studied with the x-axis rotated so it is parallel with the surface of the incline. Also, the angular motion of a simple pendulum can be recorded by choosing a polar coordinate system, placing the origin at the pivot point and rotating the horizontal axis by 90 degrees in a clockwise direction. This allows VideoPoint to report the angle data between -π and π. Figure 4-5: The origin for this popular Hershey Park water ride is set to the top of the fall and rotated such that all x values are reported parallel to the incline.

77 Video Point Manual Page 64 Figure 4-6: The origin has been moved to the axis of the pendulum and rotated such that the angles reported are in the range of -π to π. A coordinate system can be rotated through any angle between 0 and 360 in a counterclockwise direction with respect to the horizontal axis (or with respect to the positive x-axis of the coordinate system to which the rotated coordinate system refers). Figure 4-7: A selected origin with associated coordinate axes and a selected origin with axes rotated at 345 with respect to the native Video Coordinate System axes. Rotate a Coordinate System To rotate a coordinate system, the origin of the system must be selected. Once the origin is selected, there are two ways to rotate the system. One is visually and the other is to enter the desired angle into the Origin Dialog. Visual Coordinate Rotation To rotate the axes visually, select the origin associated with the coordinate system you want to rotate. If the origin is selected, it will have a circle around it with a little handle along the positive x-axis. Drag the handle around either clockwise or counter clockwise to change the angle of the coordinate system. Numerical Coordinate Rotation To rotate the axes numerically, select the origin associated with the coordinate system you want to rotate. Double click on the selected origin to bring up the Origin Dialog located at the bottom of the Edit Point Series Dialog Box.

78 Video Point Manual Page 65 Figure 4-8: The Origin Dialog at the bottom of the Edit Point Series Dialog Box. Move a Video Point Series to a Different Coordinate System You can move a data point from one designated coordinate system to another. For example, suppose you are analyzing a film of a person sitting on a cart who tosses a ball vertically while the cart is moving at a constant velocity in a direction perpendicular to the video camera. You can select the location on the ball in each frame and then create a data table showing the x and y coordinates of the ball relative to the laboratory coordinate system or to a coordinate system moving with the cart. This should help you to acquire a better understanding of Galilean relativity. Move a Video Point Series To move a video point series or point-type series to a different coordinate system, place the mouse over the left-most box in the series line in the Coordinate Systems Window and drag the series line onto the header of the coordinate system to which you want to add the series. Figure 4-9: Ball #3 starts out in the Origin 1 coordinate system but is dragged to the "Table End" coordinate system. Remove a Scale from a Coordinate System Drag the scale icon in the coordinate system header onto the Video Origin header. Since the Video Origin box cannot be scaled, it will just remove the scale from the original coordinate system.

79 Video Point Manual Page 66 Replace a Scale in a Coordinate System If you have more than one scale item on your movie, you can switch between them by dragging the scale items onto different coordinate systems. Scale Movies Choose an Object of Known Length for Scale In order to scale a movie, there has to be an object (i.e., a meter stick) of which you know the length. If the camera does not zoom, the object needs to be in only one frame of the movie. When you make your own movies, be SURE to keep something like a meter stick in the frame of the movie. Whatever you choose for your known length it is IMPERATIVE that the object be in the same plane as the motion of interest. If the object is behind the motion, the scale factor (in pixels/meters) will be too small (since the length of the meter stick is smaller on the movie). Change a Scale Once both ends of a scale item have been located on a movie, the scale factor pixels/meter) can be changed in a few ways. You can either move the locations of the end video points (closer reduces the scale factor) or change the known length of the scale itself. Change the Known Length of a Scale Item If you entered the wrong known length of the object in the movie that is used for scaling (i.e., it s a 2 meter stick and you entered 1 meter for the known length), choose Options->Change Scale... Or select the scale that you want to change in the Scale popup menu and then enter the new known length of the object or select the scale on the Coordinate System Window, then choose Edit->Selected Series and change the number in the length field Take Short Cuts Turn Off/On Automatic Movie Frame Advance If you do/don't want the movie frames to advance automatically after all the video points on this movie frame have been taken, select Options->Auto Frame Advance. Turn Off/On Automatic Point Selection If you do/don t want the next video point that needs data on each frame automatically, select Options->Auto Point Advance View and Analyze Movies Play a Movie Open a movie and bring the movie window to the front. To play the movie, you can click on the button on the movie controller. By default, the movie plays every frame as fast as it can, regardless of the original time code. If you are using a slow computer the movie may not play at a normal speed.

80 Video Point Manual Page 67 Play the Movie at Normal Speed To play the movie at the rate at which it was captured, uncheck Movie->Play All Frames. Video Point will maintain the normal play back rate by dropping frames selectively. Step Through the Movie Use the buttons on the movie controller to step forward and backwards through the movie. Sometimes you will come across a movie that has more frames than you want to analyze. Choose Movie->Set Step Size... to change the default time step of the movie. Enter the time, in seconds, that you want the movie to step through each time it auto-advances or when a step button is pressed. This does not eliminate any frames from the movie, it just skips frames. You can reset the movie step size to normal if you want to analyze frames that were previously skipped. Rewind The Movie Choose Movie->Rewind (Ctrl-R for Windows and Command-R for MAC). You can also a) click once just to the right of the button, b) drag the controller "slider" back to the beginning. Change the Display of Elapsed Times between Frames If a series of video frames have been recorded using a high speed camera or time lapse technique, then when the movie is digitized the time codes may be incorrect. You can change the elapsed times between frames by choosing Movie->Select Frame Rate. Changing this is not a good idea unless you know that the time codes in the movie are incorrect. See the "Frame Rate Dialog" entry in section 3.3 of chapter 3. View Movie Frame Times The elapsed time between each pair of adjacent frames is not necessarily constant. In most cases, it is safest and most accurate to use the movie s time code. A list of times is given in the first column of the Table Window. When most QuickTime Movies are created a time code is associated with each frame. Normally the VideoPoint software interprets this code and can display the time elapsed between the first frame and each subsequent frame when the movie was originally recorded. Resize the Movie Window You can resize the movie by using any of the default sizes (Movie->Half Size, Movie Normal Size, Movie->Double Size, or Movie->Fill Screen) There are other ways to resize- WIN: Resize the window by dragging any edge. MAC: Use the grow box in the bottom right corner to resize the window, or Use the Zoom box in the upper right corner of the window to make the window as big as the screen.

81 Video Point Manual Page 68! Movie Window Size If you want to preserve the movie aspect ratio (ratio of height to width) be sure that the Movie- >Keep Aspect Ratio is checked. Then the width of the movie will be determined automatically from the height of the resized window. Allow any Aspect Ratio If you want your Movie Window to have an unusual shape, you can uncheck Movie->Keep Aspect Ratio. Although the movie will look distorted, the data should remain accurate. Accuracy is lost in the extreme cases (i.e., the long, skinny movie or short, fat movie). Hide/Show the Frame Numbers To hide the frame numbers at the top right of the movie window, choose Movie->Show Frame Numbers. Once the frame numbers are hidden th e numbers can be displayed once again by rechoosing Movie-Show Fame Numbers. Analyze at Series of Movies Made with a Fixed Camera First, analyze the first movie of the series as you normally would. After saving your data for the first movie, choose Options->Switch Movie. The original movie will be closed, and data associated with it will be cleared and the user will be returned to the finder to choose a new movie. When the Switch Movie feature is chosen, fixed data and information about origins, coordinate systems, and scale factors will be retained. In addition, there will be no need to change scale or to redefine the coordinate system(s) type (polar or Cartesian), rotation angle or origin location being used from movie to movie. Remove a Movie from a Coordinate System Window Ordinarily a Coordinate System Window that you have set up with various coordinate systems and different video point series with masses and so on to be associated with the movie, you may want to analyze a series of similar movies, you will want to save a coordinate system and point series setup for use with other movies. This capability is especially valuable when analyzing human motions where you need to create a point series for each body segment and enter a relative mass for it. Remove movie preserves all point series characteristics. You can remove the current movie by choosing Options->Remove Movie. You can then save this "Analysis Setup" as a data file. Opening this file later will prompt you to choose a movie to analyze. Add a Movie to a Coordinate System Window that has No Movie If the Movie field at the bottom of the Coordinate System Window says Movie: None, you have a Coordinate System Window that has no movie attached. In this case select File->Open Movie... to add a movie Display Data Show the Table Window

82 Video Point Manual Page 69 If the Table Window has been closed, you can reopen it by choosing View->Data Table (Ctrl-D) or clicking on the toolbar button. Create a New Graph Choose View->New Graph... (Ctrl-G) or click on the toolbar button. This will bring up the graph dialog box. The graph dialog box allows you to choose the data to be plotted on the horizontal and vertical axes. Rescale a Graph Once a set of graph axes are chosen these axes will rescale automatically as new data from point series are recorded based on features that you locate. You can rescale a graph by clicking on the numbers next of a graph axis corresponding to maximum and minimum values and entering new maximum and minimum values from the keyboard. Another way to rescale the graph is to double click on the graph axis you want to rescale to bring up the Graph Scale Dialog box. You can also auto-scale both axes by double-clicking anywhere on the graph area while holding the control key down. Zoom in on a Graph If you want to examine part of a graph in more detail, you can enlarge it or zoom in on it by holding down the control key, depressing the mouse button and dragging the mouse diagonally across the region of the graph you want to zoom in on. If you want to restore the graph to its original scale you will need to rescale it. Copy Data to a Spreadsheet You can copy data from the data Table Window analysis or display. to a spreadsheet or word processor for additional To locate the data table and select the data that you want to copy, clicking on the [x] and [y] headers selects whole column. Choose Edit->Copy Data. Holding down the control key allows you to select non-contiguous data. Note, however, that data selected using the control key retains all the blank columns in-between, thus pasting this data in a spreadsheet may leave some blank rows.

83 Video Point Manual Page What If? 5.1. Problems I Click on the Movie to Locate a Feature and Nothing Happens Click on the toolbar button. If the cursor changes to a, clicking on the movie will locate the selected video point (as indicated in the bottom right part of the movie). If the cursor remains a one frame and try again., all video points have been located on this frame. Advance the movie 5.2. Movie Situations The is on an Incline If the motion that you are analyzing is on an incline, it is possible to move and rotate the origin such that motion on the incline is reported in just the x- or y- direction. This makes for simpler analysis. To Move an Origin If the origin has been located and is visible on the movie (like Origin 1 is by default), drag the origin on the movie to the new location by clicking on the video point where the lines intersect. Figure 5-1: The Selected Origin is rotated by dragging it's handle around to the desired angle. To Rotate an Origin s Coordinate System Select the origin once it has been located on the movie; drag the handle (the dot on the outer edge of the circle) of the origin around until the x-axis points in the desired direction. The angle of rotation between 0 and 360 degrees will be displayed in the Coordinate System Window where the header of the coordinate system you are rotating is located. I Want Data Reported in Two Coordinate Systems? You can do this by cloning the point series and associating the clone with a second coordinate system (see section 3.2 in Chapter 3). Once this is done data are reported for both the original point series relative to its coordinate system and its clone relative a second coordinate system.

84 Video Point Manual Page 71 The Camera was Moving when the Movie was Filmed? You can define a moving coordinate system that allows you to compensate for camera motions by selecting a familiar background feature as the origin in each frame. This feature allows you to analyze motions in frame sequences made from video images recorded with a hand-held camera. In short, the position of an object relative to any other object on the screen can be reported on a frame-by-frame basis. Figure 5-2: In these three frames of a Saturn IV rocket launch the camera is panning If an origin that is fixed relative to the screen is used, the data for the rocket's location will be useless. If a moving origin is located at the top of the launch tower on a frame-by-frame basis, meaningful data for the rocket's acceleration relative to the tower which is fixed to the ground can be obtained. Figure 5-3: In the graph on the left the rocket appeart to stand still when coordinate data for its position is reported relative to an origin fixed on the screen. The graph on the right shows the rocket nose's position recorded relative to a moving origin that follows the location of the top of the launch tower as the tower appears to move down the screen in each successive frame. In order to compensate for the m oving camera you will have to find an object that is stationary (such as the corner of a table) and use it as an origin. On the first frame, move the default origin (or any other origin) to the stationary location and make sure that the origin is a Frame-by- Frame or "Semi-Fixed" video point. On each frame of the movie, make sure that the origin is located at the right place. The data will all be relative to this origin and will correct for the moving camera.

85 Video Point Manual Page 72 The Camera Panned so Much that my Origin Disappears In some cases defining coordinate transformations allows you to obtain intelligible motion data of a feature or object of interest that is tracked with a panning camera. For example, the path of a broad jumper or basketball player performing a slam dunk can be reconstructed even if the camera is sweeping so broadly that background features change completely. Figure 5-4: Four frames from a movie where the camera pans so much that no stationary object is in the frames at all times. In this case the origin (marked by a white circle) is located at one of the red tiles against the wall in the first few frames. Before the red tile disappears the origin is transformed to the bottom left corner of the black rectangular heat vent (as marked by a white square). VideoPoint corrects for the motion by storing the difference in the coordinates of the red wall tile and the black heat vent based on the locations of these features in a frame in which both are visible. Figure 5-5: Graph of the y-position of the diver's waist relative to the red tile to the left of the center of the wall. An origin transformation was made in the last few frames to a black rectangular heat vent. The demonstrates that the VideoPoint origin transformation allows you to have continuous data even when objects chosen as origins leave the visible area.

86 Video Point Manual Page 73 How to Define a Coordinate Transformation Step back to the last time that the origin was in the movie. Here you will want to translate/transform the origin to a different object that is stationary but will not leave the field of view immediately. In order to get good data, the second object must be in the same plane as the first origin. In general, it is wise to choose this transformed/translated origin such that it does not leave the field of view at all. However, you can transform/translate origins as many times as necessary. The Camera Zoomed when the Movie was Filmed? You can define scale factors on a frame-by-frame basis to follow the motion of an object with a camera that is zooming in or out or to track the motion of an object moving off into the distance. For example, the acceleration of the lunar module as it ascended from the moon during one of the Apollo missions can be determined even though the camera had been programmed to zoom back rapidly. The horizontal acceleration of a drag racer can be determined even though two different fixed cameras have been used to follow it as the dragster moves off into the distance and noticeably changes its size on every frame. How to Compensate for a Zooming Camera If the camera zooms while filming the movie, the pixels/meters calibration ratio will change on every frame of the movie. In this case, you will need to set up a scale for your coordinate system that is relocated on every frame. If you have already created a scale: 1) Choose Options->Change Scale... Figure 5-6: In the case of a zooming camera it is necessary to open this dialog to change the scale from a fixed scale type to a Frame-by-Frame scale type. 2) Select the scale that you want to change (usually there is only one). 3) Change the scale type to Frame-by-Frame. This changes the video points that make up the ends of the scales from fixed video points to frame-by-frame video points. These video points, usually named Scale1A and Scale1B (the numbers change with more scales) will now need to be selected on every frame. They will automatically be selected just like any other normal video point. If you have not yet created a scale: 1) Choose Movie->Scale Movie... 2) Enter the known length of the object in the movie. 3) Select the origin of the frame that you want to scale. 4) Change the scale type to Frame-by-Frame. This changes the video points that make up the ends of the scales from fixedvideo points to frame-by-frame video points.