The Correspondence Problem in the Optical Shape and Deformation Measurement Methods

How to correctly locate and uniquely index the same image point during the optical measurements is known as the correspondence problem. It occurs when there is a need for tracking features in all of the recorded images, regardless of the number of used cameras and the number of recorded images. In this paper, we have compared the correspondence problem solutions for the passive and active single, stereo and multi-camera systems, with a special focus to the active multi-camera system, for which we present the absolute method for unique stereo pair indexing. By using a modified projection approach, we have showed that it is possible to eliminate the need for the epipolar principle from the correspondence problem solving. With the new indexing method, each pixel can be used as a separate measuring point since it has been indexed with two independent absolute phases. Searching for stereo pairs has also been reduced from the two-dimensional image domain to a one-dimensional array, where the next stereo pair is most likely the nearest neighbor to the observed one.