Abstract
The accurate calibration for a 3D profile measurement system based on structured light projection is important to the precision measurement system; however, system calibration is always complicated and time-consuming. An improved fast method is proposed to calibrate the measurement system. First, LCD monitor, as a calibration plate, displays chessboard pattern designed by computer programming, and camera captures 1 image. Then LCD monitor displays white pattern, projector projects horizontal and vertical color-encoded fringes to the LCD monitor, and camera collects 2 images respectively. A Phase-shifting algorithm is used to establish a highly accurate correspondent relationship between camera pixels and projector pixels, and projector images are generated. Next, move the LCD monitor to other 8 places, get camera and projector images which are set for camera and projector calibration respectively using Zhang’s calibration method. Compared with ordinary techniques which use expensive equipments such as two or three orthogonal plates, LCD monitor is easy-to-use and flexible, and experiments show that calibration accuracy is improved by 5 times. In comparison with traditional projector calibration method, this method decreases the number of captured images from 8 to 2 in each place and increases the processing speed. Combining camera calibration and projector calibration, the complex calculation process of integrating traditional camera calibration and projector calibration can be simplified. Experiments have been performed based on the proposed technique and good results have been obtained.
