High Dynamic Range Structured Light 3-D Measurement Based on Region Adaptive Fringe Brightness

Fringe projection profilometry is one of the main methods for active 3-D measurement, but practical problems, such as how to obtain a complete point cloud by overcoming the effects of high surface reflectivity of objects, remain to be solved. So, in this article, we propose a set of hardware devices and region adaptive structured light algorithms. First, we introduce the surface structured light measurement system adopted in this article. Second, based on the accurate optical modeling of the measurement scene, the principles for generating the adaptive optimal projection brightness are derived in detail and the process is accelerated by exploiting the speed of neural network. Meanwhile, we creatively use the chain code combined with the M-estimator sample consensus method to find the homography from the saturated region of the camera plane to the corresponding region of the projector plane for generating fringe images with adaptive brightness. Furthermore, we chose the more robust line-shifting code and binarization method for subpixel 3-D reconstruction. Experiments have shown that our work is efficient, superior, and accurate in measuring objects with high reflective surface properties.