Detection of skewed-symmetrical shape

There is a new approach to define objects qualitatively and hierarchically by generic shapes (we call them primitives) arranged by generic relations so that a class of objects has the same description and to recognize them in a parallel and bottom-up way in the image. This paper presents a method to find a skewed symmetrical pattern in the image as a higher-order primitive which is defined by lower-order primitives such as line segments, curved segments, or the pairs of segments arranged by the relation skewed symmetry since a bilaterally symmetrical figure on an arbitrarily oriented plane viewed under orthographic projection yields a skewed symmetrical figure whose axes of symmetry and skew constrain the orientation of the underlying plane. The proposed method can detect the accurate skewed symmetrical axes of not only polygonal patterns but also curved patterns in a complex image even if some parts of the patterns are occluded