30 November 2001 Optical correlation from projections of 3D objects
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Proceedings Volume 10302, Optoelectronic Information Processing: Optics for Information Systems: A Critical Review; 1030209 (2001) https://doi.org/10.1117/12.449688
Event: Optoelectronic Information Processing: Optics for Information Systems, 2002, Valencia, Spain
Abstract
Optical correlators process two-dimensional images that come from a three-dimensional world. Filters designed for object recognition of three-dimensional scenes must have the information of all possible views. This implies a large quantity of filters, especially when the object is moving with respect to the observer. Although filters designed through the synthetic discriminant functions formalism can encode information of several images, there is a practical limit imposed by the noise appearing at the correlation plane. Fast correlators are one way of solving this problem. In this work we propose a global process for detecting 3-D objects based on fast sequential correlations with filters derived from the different possible views of the target. The acquisition of these views is accomplished in a fast and simple way by means of a three-dimensional scanner based on stereovision techniques. The 3-D model of the object thus obtained is then used to compute synthetic plane views from any desired viewpoint. A compact correlator has been developed which uses fast CCD cameras for input and output, and ferroelectric SLMs (spatial light modulators) to display the scene and the sequence of filters. The process of digitizing the 3-D coordinates is described in detail, from the acquisition of the stereopair of images, the stereo-matching algorithm we use and the final integration of all data sets into a common object-centered coordinate system. Also, general engineering problems involved in the design and construction of the correlator are analysed and discussed.
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Santiago Vallmitjana, Ignacio Prades Juvells, Arturo Carnicer, Mario Montes-Usategui, Estela Martin-Badosa, Ignasi Juan I. Labastida, F. J. Rodriguez-Miguel, and R. Tudela "Optical correlation from projections of 3D objects", Proc. SPIE 10302, Optoelectronic Information Processing: Optics for Information Systems: A Critical Review, 1030209 (30 November 2001); doi: 10.1117/12.449688; https://doi.org/10.1117/12.449688
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