Introduction to Motion Video Analysis

Introduction to Motion Video Analysis LEE Kai-chiu Seconded Teacher PE SECTION, CDI Jan 2009

1 Installation Process • Download the software from the following link: http://www.hk-phy.org/mvas/

Installation Process • Extract the zip file into a single folder.

Using the MVA software (MVA.exe) – A quick guide Open a new project Choose Open Video to start a new project

The video file format allowed is mpeg (.mpeg or .mpg) or avi (with the appropriate codec installed in the computer). Choose the video file to be opened.

1 2 • Choose horizontal, vertical or 2 dimensional • Click OK after choosing the type of motion.

1 • Input Reference Data • Click OK on the dialog box and click on a point on the video screen to specify where you want to place the coordinate origin.

the coordinate origin 1 After you have marked the origin, the Reference Distance dialog box will appear.

mark two points 1 2 2 3 After marking the two points on the video screen, a yellow line joining the two marked points will appear. A Reference Distance input dialog box will also appear.

1 2 3 • In the top space, input the mass of the moving object captured in the video. In the bottom space, input the number of frames you want the video to step forward each time you capture a position data point on the video screen.

1 2 • Setting Starting Frame and Ending Frame • To decide the frames to start and end the motion data capture, using the scrollbar (or the step forward/ backward buttons on the two sides of the scrollbar).

1 2 • Capturing Motion Data Points on Video • On the video screen, click on the position of the moving object on the video screen in each frame step to capture the motion data points.

1 5 2 3 4 • Check the Show Axis and Show All Points check boxes, and then click on the Apply button to display the axes and data points.

1 • Curve Fitting and Graph Plotting Using Plot Panel • Click on the No. of Sections pull down menu and choose 1, 2 or 3 sections to be fitted.

2 1 • Click on the Fitting Methods pull down menu and choose the type of polynomial fitting you want to do on the motion data.

1 • Click on the Plot Velocity Graph, Plot Acceleration Graph or Plot Energy Graph pull down menus and choose the graph you want to plot. Best Fit Line

1 Save ProjectThe “Save Project” buttonsaves the project information into two files, namely,the filename.mvafile andthe filename_setting.txtfile. Thefilename.mva file saves information including the reference length, coordinate axes and data points etc. The filename_setting.txt file saves information about curve fitting and will exist only if you have used the Plot Panel (for graph plotting or polynomial fitting) in the project.

Video Shooting – Points to Note • Use digital camera for video recording • Place the camera 90oto the track of motion to ensure accurate results for data analysis • Fix and do not pan the camera when shooting • Record the exact motion time for data process • Use two distinct objects (such as cones) to indicate the exact motion length • Subjects should wear distinct colour clothes to differentiate from the venue background • Assign shooting order for subjects to ensure correct data collection

THANK YOU

Introduction to Motion Video Analysis