ESTIMATING CIRCULAR SHAPE USING BINOCULAR STEREOPSIS AND TWO-SOURCE ACTIVE ILLUMINATION

To become versatile and generally useful, a robot vision system must be able to deal with specular objects, deliver uncertainty measures of recovered data and supply information that can easily be used for CAD–to–vision matching. All this has proved to be difficult.

This paper describes stereopsis using two controllable point sources in combination with two–cameras. The point sources are switched on sequentially which results in four images, two from each camera view. By studying intensity changes between the two illumination conditions, the stereo matching is simplified, it is possible to recover cylindrical shape and calculate covariance of the retrieved range and shape data.

When an object is turned, the cutting edge gives an inherent surface structure that gives very prominent reflection characteristics. These reflections are very likely to be observed and can, in the applicable cases, be used to retrieve object shape and pose. The paper is concluded by a number of experiments that show recovered range and shape data with estimated uncertainty. Recovered range data has been exported to a CAD system to illustrate the CAD–vision connection and to be able to compare range data with geometrical object models.