Monday, April 28, 2014

Tracker FAQ for students and teachers by

Learning Point of Performance Task by Leong Tze Kwang
thank bro for sharing

Having trouble with your tracker PT? Here's some FAQ that will help you.

Q1: When I shift-click on the object, it doesn’t track.

A1: Just left click on Object A and try again. If everything fail, save your file and restart tracker.

Q2: When I analyzing my graph by double clicking it, it looks like a line (or a dot).

A2: It was zoomed in too much. Simply right click (double click track pad) on the graph and choose auto scale.

Q3: My acceleration graph is super messy even though it’s supposed to be constant acceleration.

A3: The acceleration is derived from the velocity, which is in turn derived from the displacement you clicked. Any error in clicking is magnified. Using the gradient of the velocity-time graph (using the best fit function) to find the average acceleration is more reliable.

Q4: I saved my tracker file (.trk) but when I open it it’s blank.

A4: Instead of double clicking to open the tracker file, drag the trk file into the tracker software.

Q5: I opened the tracker file but there’s no video.

Q5: Simply drag the video file into the tracker. The trk file and the video file need to be saved in the same folder for the tracker to find the file. Any movement of the files will need to be manually linked by dragging the file into tracker.

Q6: My video has some skip frames or repeated frames.

A6: Different camera record video at different frame rate (some camera can set the frame rate). Using a software to trim the video often results in changing the frame rate. It’s best that you use the original video but only track the duration of interest by setting the starting and ending frame instead of using another software to trim the video.

Q7: My ball (or whatever object) looks like a line instead of a ball.

A7: Most low end camera (such as phone camera) are not suitable for capturing high speed motion. Simply track the middle of the elongated object. For futther improvement, use a better camera such as DSLR camera or the Photonics high speed camera (Set it to 120 FPS). Improving the lighting (such as shooting under bright sunlight at 12 pm) will also improve the video quality.

Please add on to the list.