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Proceedings Paper

Color fringe projection system based on optimum frequency selection
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Paper Abstract

In this paper, we present a new color fringe projection system based on optimum frequency selection and discuss its implementation. Recent results in optimum frequency selection in temporal phase unwrapping have shown that the resolution limit of commercial data projectors is reached using 3 different sets of projected fringes with different pitch. Therefore, there is a synergy between optimum fringe projection and commercial color (RGB) projectors and cameras offering the potential for parallel data acquisition and simultaneous measurement of surface color parameters. The hardware of the system is comprised of a Digital Light Processing (DLP) video projector, a color 3-chip CCD camera and a personal computer supporting two monitors. The software is developed in Microsoft Visual C++ and OpenGL. The phase calculation algorithm is based on the optimum three-frequency selection, so it has a maximum reliability to determine the fringe order and can obtain 3-D shape of an object with large slope changes or discontinuities on the surface. Since each RGB color channel carries a fringe pattern of a certain pitch, any coupling between the color channels from the projector to the CCD camera affects the phase measurements obtained. Commercially available systems inherently contain crosstalk and we compare some methods to decrease the coupling effect. As absolute fringe order is determined by heterodyning between fringes with different pitch that are imaged in separate color channels, chromatic aberration can cause incorrect calculation of fringe order. We have investigated the most sensitive heterodyne process and the color channels with minimum chromatic aberration to mitigate these effects. We also give a novel software method to further compensate for chromatic aberration. Results show that our system has the advantages of fast acquisition, large dynamic range, robustness in discontinuities, and potential color extraction.

Paper Details

Date Published: 14 August 2006
PDF: 12 pages
Proc. SPIE 6292, Interferometry XIII: Techniques and Analysis, 62920S (14 August 2006); doi: 10.1117/12.679849
Show Author Affiliations
Zonghua Zhang, Heriot-Watt Univ. (United Kingdom)
Catherine E. Towers, Univ. of Leeds (United Kingdom)
David P. Towers, Univ. of Leeds (United Kingdom)

Published in SPIE Proceedings Vol. 6292:
Interferometry XIII: Techniques and Analysis
Katherine Creath; Joanna Schmit, Editor(s)

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