A New Calibration Method of the Projector in Structured Light Measurement Technology

The calibration of the projector is necessary in the structured light measurement system with only single projector and single camera. A new calibration method of the projector with a checkerboard calibration target and a specific projecting grid pattern is proposed. The method is divided into the following steps. First, during the calibrating process, at each position of the target, one photo is captured for the checkerboard target, and another is taken with the projector projecting the specific grid pattern on the target. Second, the camera is calibrated by Zhang Z's method using the captured photos of checkerboard target. Third, image binarization, skeletonization, Hough transform and corner detection are used to obtain the pixel coordinates of feature points in the photos of grid pattern. Further, the 3D world coordinates of feature points can be calculated by the pinhole imaging model based on results acquired by Step 2 and Step 3. Since the coordinates of the feature points in the pattern are previously configured, the parameters of projector are finally calculated via the 3D world and configured pixel coordinates of the feature points. The calibration device is easy to setup and the calibrating speed is fast. Experimental results prove the effectiveness and accuracy of the method.