Arrangement for sensing the surface of an object independent of the

Abstract

A plurality of projectors are positioned in spaced relationship about an object with a surface to be geometrically analyzed. The projectors have cooperating masks which project onto the object illuminated patterns that subdivide the object into predetermined sections. Each mask has a predetermined pattern of sections, and is applied in sequence. The masks are cooperatively advanced in the projectors, with a separate illuminating pattern prevailing on the object each time that the masks are advanced. The combinations of the patterns on the masks define closely-spaced sections subdividing the object. The patterns are coded so that each section is uniquely defined in coded form. Cameras having the entire object within their field of view, photograph the object each time a separate mask is applied. To sense sections of the surface independent of the reflectance characteristics of the surface, the projectors direct two separate illuminating signals at the object surface. The two illuminating signals are inversely related to each other, and after they are recorded by the cameras, the recorded signals are subtracted from each other to result in a waveform having points at which the subtraction yields zero values. These points are then used to define the projection field.