Abstract
A problem of the stereo vision is that measurement error occurs for curved objects. Boundaries of curved objects can be classified to two classes; discontinuity boundaries where two surfaces intersect physically and positions of discontinuity boundaries where a surface turns smoothly away from the viewer. The 3-D positions of disconinuity boundaries can be obtained by the stereo method, but measurement error occurs for the extremal boundaries. On the other hand, at an extremal boundary the surface orientation can be obtained by“shape from contour”method. Therefore, to get the 3-D information of curved objects it is necessary to classify boundaries to two types; however, few method has been proposed so far.
In this paper, we propose a method to classify boundaries to two types by trinocular vision. When a curved object is viewed from two cameras, the intersecting point of two lines of sight is on the discontinuity but is not on the extremal boundary. This gap between the intersecting point and the boundary can be detected by the third camera: thus discriminating the extremal from the discontinuity boundary. We have made experiments on several types of cylinders and obtained satisfactory results.
