Correspondence problem

The correspondence problem refers to the problem of ascertaining which parts of one image correspond to which parts of another image,[1] where differences are due to movement of the camera, the elapse of time, and/or movement of objects in the photos.

The problem is made more difficult when the objects in the scene are in motion relative to the camera(s).

To avoid the aperture problem a good feature should have local variation in two directions.

The correspondence problem is also the basis of the particle image velocimetry measurement technique, which is nowadays widely used in the fluid mechanics field to quantitatively measure fluid motion.

A simple method is to compare small patches between rectified images.