Multiple-line full-field laser-camera range sensor

Jonathan Kofman; Jeffrey T. Wu; Kiatchai Borribanbunpotkat

doi:10.1117/12.754551

8 October 2007 Multiple-line full-field laser-camera range sensor

Jonathan Kofman, Jeffrey T. Wu, Kiatchai Borribanbunpotkat

Proceedings Volume 6718, Optomechatronic Computer-Vision Systems II; 67180A (2007) https://doi.org/10.1117/12.754551
Event: International Symposium on Optomechatronic Technologies, 2007, Lausanne, Switzerland

Abstract

Optical methods based on structured-light projection are typically used for three-dimensional (3D) surface-geometry measurement as the methods are non-contacting. Single-line projection techniques are most commonly used; however, they require a translation or rotation stage to scan the range-sensor head across the object surface. Phase-shifting fringe projection full-field methods have been commonly used with projection of two to four fringe patterns during measurement. Simultaneous projection of multiple structured-light lines is a practical alternative full-field method as it offers the advantage of range image capture using a single image or simultaneously captured image pair. This paper presents a multiple-line full-field laser-camera range sensor, calibrated using a novel 2-D image-plane to 3D-object-space mapping. The sensor employs a 31 laser-line projector and two CCD cameras. To calibrate the system, 31 laser lines were simultaneously projected onto a black plate with horizontal line markings of known spacing. Images were acquired with the plate at 6 known depths over a 200 mm range of depth. After conical diffraction correction was applied to the object-space coordinates for all points, a mapping of 2D image coordinates to the known 3D object-space coordinates was carried out for each of the 31 laser projections using closed-form Bezier surface fitting. The mean of the absolute value of the calibration errors were 0.010 mm and 0.010 mm in X, 0.598 and 0.465 mm in Y (vertical), and 0.190 mm and 0.189 mm in Z (depth), for the two cameras, respectively. The method has the advantage that no knowledge of the geometry of the laser-camera setup is required and accurate alignment of the laser and camera is not necessary. The calibration technique also accounts for any lens distortion from the low cost cameras.

Citation Download Citation

Jonathan Kofman, Jeffrey T. Wu, and Kiatchai Borribanbunpotkat "Multiple-line full-field laser-camera range sensor", Proc. SPIE 6718, Optomechatronic Computer-Vision Systems II, 67180A (8 October 2007); https://doi.org/10.1117/12.754551

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