Abstract
It is the foundation that the absolute fringe order is discerned, in the 3-D image measurement methods, such as spatial pattern projection technique and moir? topography. The reason is that the depth range of the object is computed from correspondence relation between the fringe order of a reflective pattern and the depth of an object. Multiple images are need by the conventional method for discern the fringes order. Moreover, it has a problem of phase unwrapping in the phase analysis method of moir? pattern or other interfering pattern. So it is difficult to calculate the absolute phase or to discern the relation between the fringes, especially in cases of which the fringes are discontinuous or the objects are isolated, and so forth. The technique of using modulation projection with 3-D information is presented. New fringes pattern whose fringe intensity or color changes with its order is produced. Thus the fringe order can be extracted easily from the fringe intensity or color, and then the absolute phase and the absolute depth range can be obtained solely also. This technique needs only single image or double images.