Estimation of the orientation and shape features of objects in images fromthe angular dependence of the length of a radius vector

A method for determining the orientation of an object in an image (the prin cipal axis of the object serves as one of the axes of its internal coordina te system), which involves finding the maximum value of the symmetry factor of the object (the ratio between the areas of the intersection and union o f the object and the result of a symmetry transformation performed on it) i s developed. A technique for estimating the symmetry factor, which utilizes a description of the shape of the object in the form of a function of the length of the vector joining the center of gravity and the boundary of the object on the angle of this vector, is proposed. This function permits fair ly simple estimation of the values of the shape features of objects in imag es: the aspect ratio, the ratio between the radii of inscribed and circumsc ribed circles, the axial and central symmetry factors, and the roundness fa ctor. (C) 2000 The Optical Society of America.