sentences:  If the shape S has a composite structure consisting of subparts "S1", "S2", .. "SN" and the reference points for the shapes "S", "S1", "S2", .. "SN" are "y", "y1", "y2", .. "yn", respectively, then for a scaling factor "s" and orientation "θ", the generalized Hough transform "Rs(ɸ)" is given by formula_1.The concern with this transform is that the choice of reference can greatly affect the accuracy.To overcome this, Ballard has suggested smoothing the resultant accumulator with a composite smoothing template.