Measurement of the 3D shape of objects based on the structured light techniques has found numerous applications in scientific and commercial fields due to their fast speed and non-contact nature. Typically, a sturctured light system consists of a camera and a projector in which the projector projects specially designed patterns on the objects, while the camera captures images of the paterns. By analyzing the captured images of the patterns, the 3D shape of objects are derived and the difficult corresponding problem in a classic stereo vision system is alleviated. However, the structured light system must be fully calibrated prior its usage. Although numerous approaches to calibrate a structured light sytem are reported in the literature, many difficult problems persist in the real progress of applications. This thesis is focused on the flexible, general, and accurate calibration techniques. The main work can be summarized as follows: 1)In the current available calibration methods for the structured light system, either the expensive equipments are used or the calibration procedures seem completed and time-consuming. We propose a flexible technique to easily calibrate a sturctured light system based on the homography induced by a model plane. The total procedure only requires two patterns, one is attached to a model plane, the other is projected on the model plane by a LCD projector. In order for the projector to see the calibration board like a camera, two approaches are proposed, one is called the black-and-white checkerboard method, the other is the red-and-blue checkerboard method. At each position, only one or two images need to be caputured, and the calibration procedure is completely automatic. The proposed technique is easy to use and efficient. 2)For a portable structured light system, the calibration method must be easy to use and flexible. A flexible calibration method is proposed to meet the requirements of the portable structured light system through a surface plane based on cross ratio and epipolar geometry. The special calibration board and reference board are designed, and the calibration procedure is completed and rather accurate with one model plane. 3)There would be more errors if the color phase-shifting technique were dirctly used for 3D shape measurement due to the nonlinear response curve, coupling and imbalance of projector and camera. Several compensating modules, including polynomial fitness, coupling evaluated matrix, balance of different channels and so on, are proposed to correct these errors.
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