Tridimensional invariant correlation based on phase-coded and sine-coded range images

New methods for recognition of range images based on correlation are presented. The techniques allow the detection of a range image of a tridimensional pattern whatever its position along the x , y and z axes. The first method uses the phase-coding of the range image in order to obtain invariance along the z -axis in the correlation process. The second method uses the sine-coding of the range image in order to obtain better discrimination than that obtained with phase-coding. The third method is a hybrid one that makes use of sine-coding for the input scene and phase-coding for the reference image, so both the full translation invariance and high discrimination abilities are obtained. Computer simulations are presented. Also, an experimental implementation of the method has been carried out showing good agreement with theoretical predictions.