Computing location and orientation of polyhedral surfaces using a laser-based vision system

A system for determining the 3-D location and orientation of polyhedral surfaces is proposed. 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. Based on the vanishing points or the directly available line directions of the perceived grid lines on the polyhedral surface, the polyhedral surface orientation is inferred. The given dimensions of the grid pattern on the plate are used to estimate the depth information of the polyhedral surfaces. The noise problem that occurs in the real image is solved by a least-squares-estimation method and an iterative refinement method based on a geometric constraint criterion. Experiments conducted to provide practical insight into the method indicate that the method is accurate and stable