3-D cues from a single view: detection of elliptical arcs and model-based perspective backprojection

complexity of the scene which can be formed by several partially occluded objects (e.g. the bin-picking task). We describe the use of geometric reasoning and proI n t h e l i t e r a t u r * J t i s P° s s i b l e t o find <&* a TMmbe o f jective geometry to infer 3-D information about cirm e t h o d s f o r e l h P t i c a l 8 b u t t h e P r o b l e m o f d e a l i n 8 cles which project elliptical curves onto one 2-D imefficiently with real images has been often ignored. age. A robust and efficient method to extract elliptical arcs starting from chains of line segments obtained by the polygonal approximation of edge curves is presented. Then an algorithm that solves analytically the problem of the perspective inversion of an elliptical arc from its projection onto the image plane is outlined. Finally experimental results on real images of mechanical parts are reported; therefore, current drawbacks and future extensions of this work are discussed. Preprocessing f Polygonal (Approximation \ ^ Chains