Photogrammetric Aspects of the Heterodyne Optical Correlator.
Abstract
Heterodyne optical correlation as applied to coherently illuminated overlapping transparencies is briefly discussed. Photogrammetric aspects of optical image coincidence are carefully studied for vertical as well as tilted photography. An experimental Heterodyne Optical Correlator (HOC) is described. A two-dimensional photo diode detector array is used in the output plane as a precise measuring system. It is shown that for regular aerial photography, it is not possible to place the transparencies untilted in the correlator and expect tolerable y-parallaxes. Therefore, either the transparencies must be tilted, or the HOC should operate essentially as a comparator, with correlation taking place in the image space. For the latter case, one transparency is fixed and the other is moved in steps in both the x- and y- directions. The result is that for each array element one gets x, y coordinates on one transparency and px, py parallaxes from the other. The results of two preliminary tests using aerial photography are given. They indicate accuracies of about one to two parallax steps (one step = 25 micrometers in the tests). However, the tests are so limited that the results should be considered only as preliminary, indicating the feasibility of the system as an area correlator. Further development and more extensive testing are recommended before the potential and accuracy of the HOC system may be determined. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 01, 1976
- Accession Number
- ADA038497
Entities
People
- Edward M. Mikhail
Organizations
- Purdue University