Showing papers on "Digital image correlation published in 1976"

Experimental heterodyne optical correlator

Abstract: : Over the last several years considerable progress has been made both with regard to the demonstration of the basic concepts of heterodyne optical correlation (HOC) systems as well as the evaluation of the potentials of such a system to achieve automation of the stereocompilation process. This document is the final technical report on a detailed study to test, analyze and achieve optimisation of the experimental HOC system design. The heterodyne optical correlation system is a generalized optical correlation system having significant advantages in its application to stereocompilation. The detection of the regions of conjugate image coincidence between two transparencies through image correlation forms the basis for most automated stereocompilation system. In the HOC system the two transparencies forming the stereopair are relatively oriented and projected onto a common image plane where coincidence is detected. By means of heterodyne optical techniques a normalized correlation coefficient is measured at each element of a photodiode array in the common image plane. The normalized correlation values are then used to define regions of conjugate image coincidence for a given orientation between transparencies.