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Proceedings Paper

Repeated phase-offset measurement for error compensation in two-step triangular phase-shifting profilometry
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Paper Abstract

Two-step triangular phase-shifting is a recently developed method for 3-D shape measurement. In this method, two triangular gray-level-coded patterns, which are phase-shifted by half of the pitch, are needed to reconstruct the 3-D object. The measurement accuracy is limited by gamma non-linearity and defocus of the projector and camera. This paper presents a repeated phase-offset two-step triangular-pattern phase-shifting method used to decrease the measurement error caused by the gamma non-linearity and defocus in the previously developed two-step triangularpattern phase-shifting 3-D object measurement method. Experimental analysis indicated that a sensitivity threshold based on the gamma non-linearity curve should be used as the minimum intensity of the computer-generated pattern input to the projector to reduce measurement error. In the repeated phase-offset method, two-step triangular phaseshifting is repeated with an initial phase offset of one-eighth of the pitch, and the two obtained 3-D object height distributions are averaged to generate the final 3-D object-height distribution. Experimental results demonstrated that the repeated phase-offset measurement method substantially decreased measurement error compared to the two-step triangular phase-shifting method.

Paper Details

Date Published: 18 October 2006
PDF: 8 pages
Proc. SPIE 6375, Optomechatronic Sensors, Instrumentation, and Computer-Vision Systems, 63750D (18 October 2006); doi: 10.1117/12.690735
Show Author Affiliations
Peirong Jia, Univ. of Ottawa (Canada)
Jonathan Kofman, Univ. of Ottawa (Canada)
Univ. of Waterloo (Canada)
Chad English, Neptec Design Group Ltd. (Canada)

Published in SPIE Proceedings Vol. 6375:
Optomechatronic Sensors, Instrumentation, and Computer-Vision Systems
Jonathan Kofman; Yasuhiro Takaya, Editor(s)

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