1 October 1974 Contour Generation Using Fourier Transform Filters
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Proceedings Volume 0045, Coherent Optics in Mapping; (1974) https://doi.org/10.1117/12.953974
Event: Coherent Optics in Modeling, 1974, Rochester, United States
Abstract
The last decade has seen an increasing inter-est in developing alternatives to manual stereocompilation. These new methods have ranged from electronic cross-correlation to optical cross-correlation and match filtering (Ref. 1-3). This paper discusses a technique of generating a complete set of contours using a relatively simple optical apparatus. Over-lapping stereophotographs are coherently summed using a Mach-Zehnder Interferometer. For vertical photography the y-parallax can be removed by proper orientation of the film plates and the only remaining x-parallax is due to terrain elevation differences. This parallax will result in a grating-like structure that can be bandpass filtered in the Fourier Transform plane to pass some given grating spacing and the corresponding parallax. The filtered image will contain a constant parallax contour, which for vertical photography is a constant height contour. Since the grating-like structure is not sinudoidal, higher order frequencies will be present and harmonic frequencies corresponding to multiples of the parallax associated with the filter frequency will also be present and produce additional contour fringes at a reduced modulation in the image.
© (1974) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
John R. Benton, John R. Benton, } "Contour Generation Using Fourier Transform Filters", Proc. SPIE 0045, Coherent Optics in Mapping, (1 October 1974); doi: 10.1117/12.953974; https://doi.org/10.1117/12.953974
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