An active range imaging system based on triangulation between a projected grid and an image viewed by a camera is discussed. The geometry of the imaging system is designed to readily accommodate a calibration of both the camera and the projected grid using 2-D calibration objects. A new improved grid design is presented to increase the volume where the correspondence of range points can be resolved unambiguously. The steps needed to extract range information from the production of the camera image are reviewed. This review includes the image processing techniques needed to extract the location of range points in the camera image by resolving the correspondence between projected and imaged range points using the principle of connectivity and a simple "look up" table produced off-line during the calibration. Finally, the calculation of range data based on triangulation is presented, together with experiments to demonstrate the general performance of the imaging system.
Timo A. Vuori,
"Three-dimensional imaging system with structured lighting and practical constraints," Journal of Electronic Imaging 6(1), (1 January 1997). https://doi.org/10.1117/12.251156