A laser-based vision system for computing the location and orientation of 3-D polyhedral surfaces is proposed. In this system, an expanded laser beam Passes through a code plate marked with equally spaced vertical and horizontal lines and impinges on a polyhedral object to create a spatial-encoded image for analysis. Then, based on the vanishing points or the directly available line directions of the perceived grid lines on the polyhedral surface, the polyhedral surface orientation can be inferred. In the meantime, the given dimensions of the grid pattern on the Plate are used to estimate the depth information of the polyhedral surfaces. More importantly, we shall solve the noise problem that occurs in the real image by a least squares estimation method and an iterative refinement method based on a geometric constraint criterion. Experiments are conducted to provide practical insight into the method. The experimental results indicate that the method is remarkably accurate and stable.
