Natural shape detection based on principal component analysis

The classical Hough transform, the generalized Hough transforms, and their extensions are quite robust for detection of a large class of objects that can be categorized as industrial parts. These objects are rigid and have fixed shapes, i.e., different instances of the same object are more or less identical. These techniques, and indeed most current techniques, however, do not adequately handle shapes that are more flexible. These shapes are widely found in nature and are characterizedby the fact that different instances of the same shape are similar, but not identical, e.g., leaves and flowers. We present a new technique to recognize natural shapes, based on principal component analysis. A set of basis shapes are obtained using principal component analysis. A Houghlike technique is used to detect the basis shapes. The results are then combined to locate the shape in the image. Experimental resuits show that the approach is robust, accurate, and fast.