Using VidSync for 2-D Measurement
Although VidSync generates the most accurate measurements using the full 3-D method, for some studies 2-D measurement is more convenient and adequately accurate. This works best when the subjects of the observations are approximately confined to a single plane; for example, it would be very suitable for measuring the positions of ants running around on a floor, or fish in a shallow tank of water, both viewed from high above.
The mathematics required for 2-D measurement are an intermediate step in VidSync's 3-D measurement process, so the usage of the program is very similar. While 3-D measurement requires two cameras, 2-D measurement only requires one (though you may use more). If you do use just one clip, you will need to activate advanced playback controls under File -> VidSync Preferences -> Misc -> "Show advanced playback controls with only one video clip loaded." The calibration frame for 2-D measurement can be a single flat grid of dots (instead of two dot surfaces like in the 3-D method) placed in roughly the same plane as the measurement subjects. Distortion correct works in the same way it does for 3-D measurements.
When you calibrate a video clip for 2-D measurement, some of the calibration output numbers will show up as zeros. For example, the camera position is displayed at (0,0,0), but those are not the coordinates of the camera. It just cannot be determined with this method.