Range image accuracy improvement by acquisition planning

The recent requirement for increased speed in the design and manufacturing of new products led to a rapid evolution of the technics for fast production (rapid prototyping, machining at high speed, etc.). But a significant component did not follow this evolution, that is the dimensional and functional checking process, which is most of the time carried out in a traditional way. The use of range sensor allows very significant improvement in acquisition speed but does not equal the accuracy obtained with a coordinate measuring machine. In order to obtain a quality control close to that obtained in metrology, we suggest to improve the accuracy of the depth measurements by following an acquisition strategy. We propose in this paper such a strategy to automatically produce a sensing plan for completely and precisely acquiring the geometry of a surface or of a complete piece whenever possible. The system requires the exact position and orientation of the part and its CAD model in IGES format. There is no limitation regarding the shape of the part to be digitized. A Biris sensor was used, and for this sensor, the precision of the 3D measured points is function of the distance and of the incident angle with which the laser beam reaches the surface. Our strategy guaranties that the viewpoint found meets the best precision conditions in the scanning process.