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Proceedings Paper

Extrinsic calibration of a 3D sensor based on an array projector and a single camera
Author(s): Eugene Wong; Stefan Heist; Christian Bräuer-Burchardt; Andreas Stark; Holger Babovsky; Richard Kowarschik
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Paper Abstract

We previously presented a technique calibrating a Multi-Aperture Array Projector (MAAP) for performing high-speed three-dimensional (3D) surface topology measurements with structured illumination. The MAAP achieves projection rates up to 3 kHz by projecting a sequence of aperiodic sinusoidal fringes through several distinct projecting aperture channels such that up to 330 3D measurements per second could be achieved. This rapid switching between several projecting channels overcomes the projection limit of conventional off-the-shelf single aperture Digital Light Processing (DLP) or Liquid Crystal on Silicon (LCoS) technologies that typically have projection rates on the order of 100 Hz. The proposed MAAP calibration technique re-enabled photogrammetric 3D measurements to be made using a single CCD or CMOS camera where a stereo-camera setup used to be required for triangulation. The focus to reduce a stereo-configuration to a single camera system opens possibilities to decrease cost as well as form factor of such a high-speed metrology system utilizing an MAAP. For such a photogrammetric optical metrology system, intrinsic camera calibration and extrinsic setup calibration are vital to obtain high measurement performance. With the pinhole camera model assumption, intrinsic calibration is typically carried out using the standard Zhang method. However, there is currently no such standard technique that can comprehensively perform the required extrinsic calibration. In this study, the main sources of measurement error arising from extrinsic calibration of the proposed technique are discussed and investigated. Several different extrinsic calibration techniques are proposed and the resulting measurement performance evaluated.

Paper Details

Date Published: 21 June 2019
PDF: 8 pages
Proc. SPIE 11056, Optical Measurement Systems for Industrial Inspection XI, 1105617 (21 June 2019); doi: 10.1117/12.2530130
Show Author Affiliations
Eugene Wong, Friedrich-Schiller-Univ. Jena (Germany)
Stefan Heist, Friedrich-Schiller-Univ. Jena (Germany)
Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Christian Bräuer-Burchardt, Fraunhofer-Institut für Angewandte Optik und Feinmechanik IOF (Germany)
Andreas Stark, Friedrich-Schiller-Univ. Jena (Germany)
Holger Babovsky, Friedrich-Schiller-Univ. Jena (Germany)
Richard Kowarschik, Friedrich-Schiller-Univ. Jena (Germany)

Published in SPIE Proceedings Vol. 11056:
Optical Measurement Systems for Industrial Inspection XI
Peter Lehmann; Wolfgang Osten; Armando Albertazzi Gonçalves Jr., Editor(s)

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