Color-Encoded Digital Fringe Projection Technique For High-Speed 3-D Shape Measurement: Color Coupling And Imbalance Compensation

Color-encoded digital fringe projection is a recently developed technique for high-speed 3-D shape measurement. In this technique, only a single image is needed for reconstructing the 3-D surface shape of an object. Thus the measurement speed can he increased up to the frame rate of the camera. However, previous experimental results showed that the measurement accuracy of this technique was lower than that of the traditional grayscale technique due largely to the color coupling and imbalance problems. In this research, we propose an improved system with a high brightness LCD projector and a 3-CCD video camera to address these problems. A Look-Up-Table (LUT) method is developed to compensate for errors caused by color coupling and imbalance. In addition, a nonlinearity compensation method is used to further reduce measurement errors. Experimental results showed that the measurement error was significantly reduced.