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Proceedings Paper

Efficient correspondence search algorithm for GOBO projection-based real-time 3D measurement
Author(s): Patrick Dietrich; Stefan Heist; Peter Lutzke; Martin Landmann; Pascal Grosmann; Peter Kühmstedt; Gunther Notni
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Paper Abstract

Many robot-operated automation tasks require real-time reconstruction of accurate 3D data. While our sensors that are based on GOBO projection-aided stereo matching between two cameras allow for high acquisition frame rates, the 3D reconstruction calculation is really time consuming. In order to find corresponding pixels between cameras, it is necessary to search the best match amongst all pixels within the geometrically possible image area. The well-established method for this search is to compare each candidate pixel by temporal cross correlation of the brightness-value sequences of both pixels. This is computationally intensive and interdicts fast, real-time applications on standard PC hardware. We introduce a new algorithm, which minimizes the number of calculations needed to compare two pixels down to two binary operations per comparison. To achieve this, we pre-calculate a bit-string of binary features for each pixel of both cameras. Then, two pixels can be compared by counting the number of bits that differ between the two bit strings. Our algorithm's results are accurate to a few pixels and require a second, cross correlation-based refinement. In practice, our algorithm (including pre-calculation and refinement step) is much faster than traditional, purely cross correlation-based search, while maintaining a similar level of accuracy.

Paper Details

Date Published: 13 May 2019
PDF: 8 pages
Proc. SPIE 10991, Dimensional Optical Metrology and Inspection for Practical Applications VIII, 1099109 (13 May 2019); doi: 10.1117/12.2518641
Show Author Affiliations
Patrick Dietrich, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Friedrich-Schiller-Univ. Jena (Germany)
Stefan Heist, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Friedrich-Schiller-Univ. Jena (Germany)
Peter Lutzke, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Martin Landmann, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Friedrich-Schiller-Univ. Jena (Germany)
Pascal Grosmann, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Peter Kühmstedt, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Gunther Notni, Fraunhofer-Institut für Angewandte Optik und Feinmechanik (Germany)
Ilmenau Univ. of Technology (Germany)


Published in SPIE Proceedings Vol. 10991:
Dimensional Optical Metrology and Inspection for Practical Applications VIII
Kevin G. Harding; Song Zhang, Editor(s)

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