In our experience people often don’t know how to distinguish between a planar tracker and a point tracker. Thus, we’d like to give you a brief overview on both approaches and especially the tracking results of each.
A point tracker follows one single 2D point through a video sequence, based on the direct visual neighborhood of the point, with no regard of further information. As soon as the appearance of the neighborhood changes (e.g., due to perspective movements, occlusion or lighting conditions) the tracked point often drifts to other locations in subsequent video frames. Further, especially if the location of the initial point leaves the video footage (e.g., due to panning of the camera) point trackers fail completely. That’s why pointer trackers often need manual user adjustments to end up with a suitable tracking result. Finally, a tracked point can be used as simple 2D anchor for new digital content like text, logos or animated graphics. However, the integration is a overlay not adapting to perspective changes or changes in depth. Here’s an example for a point tracker:
A planar tracker follows a whole planar area through a video sequence. It observes pixels and structures and tracks how they change during the sequence to calculate position, perspective and scale etc. Due to the amount of information the tracker can handle more complex use-cases than a point tracker. Of course, the amount of information can lead to a longer tracking time in comparison to the point tracker. A planar tracker delivers more advanced tracking results that are organically fitting into the perspective environment of the footage for more realistic inserts. The inserts stay authentically integrated even when the object or area moves. Here’s a video about a planar tracker:
Furthermore, there’s a difference between a 2D planar tracker, that only follows a plane area with no regard of the appearance of the neighborhood, and a 3D planar tracker, that not only follows the masked planar area but generates a whole 3D world in the background. This enables to move the integrated content wherever you like within the scene and to modify it in any way (e.g. rotate or translate the insert). We show this feature here:
Summing it up: Point and 2D or 3D planar trackers are different approaches delivering individual results. It always depends on your purpose which tracker you should use but you definitely should be aware of the differences.