Ball/Court Interaction Analysis

Adobe Premiere video editing software was used to edit and catalog the video clips on the computer. A combination of Measurement In Motion analysis software by Learning in Motion, Inc. and Microsoft Excel spreadsheet software were used to conduct the data collection and analysis.

The digitizing process consists of playing back the ball bounce clips and using the computer's digitizing capabilities to capture (or transfer) the video onto storage media such as a hard drive. The video was recorded at 250 frames per second, but to keep the file sizes manageable the data was digitized at 125 frames per second. Because standard video plays back at 30 frames per second the video is then slowed down by 4.2 times from real time.

Though many more parameters can be isolated, our analysis will concentrate on the following information:

The digitized video is now analyzed in Measurement In Motion (MIM). This is done by tracking the ball's center throughout its trajectory. Other necessary elements such as scale and origin are marked to conduct the analysis.

From this information, MIM is able to generate a set of coordinates corresponding to the ball trajectory. This coordinate set is then imported in Excel for further manipulation.

Excel's interpolating feature was used to smooth the coordinate data because of the limited number of points in a bounce sequence (only about a hundred points) and the limited resolution. A curve fit was then applied to the ball bounce trajectory using a second order polynomial. All of the analysis was then conducted on the interpolated data. The empirical data and the interpolated data were compared to confirm the validity of the interpolation. In order to correlate each data sets, the moment of impact was chosen as time zero. All the data was synchronized in this manner.