Spiral arc shape representation for automatic inspection of surface mount assemblies

Describes an efficient technique for representing 2D shapes, by approximating their contours with segments of spiral arcs. By definition a spiral arc is one which exhibits monotone curvature along the arc length, straight line segments and circular arcs being special cases. The arc is specified by giving the position of each endpoint, plus the orientation of the tangent to the arc at each endpoint. For a straight line or circular arc this information specifies the curve uniquely. For other arcs a formula is given for generating an arc between the two points. This formula minimizes the curvature of the arc subject to various smoothness constraints. The generated arc may only approximate the true contour to within a specified level of tolerance, where the degree of tolerance constitutes a scale space parameter