Calibration of the structured light system based on active projection

The camera-projector systems are widely used in 3D measurement. In the visual measurement systems, the calibration for the camera and projector is an important issue. In this paper, an active projection method based on homography is presented for the camera-projector system calibration. With the camera visual feedback, the features of the target and the projected image are extracted by color channels. The homography matrix is calculated, and then images in the projector are pre-warped. Finally the projected image is exactly matched with the printed pattern of the target. In this condition, the projector can be modeled as an inverse camera model, thus the projector calibration can be achieved by camera calibration approaches. Another advantage of our approach is that the projector can be automatically aligned to the target via the use of visual feedback. The experimental results are presented to verify our approach.