Detection and localization of the top object in the stack of objects

Abstract

This paper proposes a new algorithm that detects the top object in a stack of arbitrarily overlapped objects, using the fact that the boundary edges of an occluding surface are not disconnected by other edges. To determine whether a surface is an occluding one or occluded one, this paper represents the objects in an input image using the attributed relation graph where a node represents a surface and an arc connecting two nodes shows the adjacency of the two surfaces in the image. An arc is weighted by two relation values, each of which is weighted on a node and tells the number of edges shared with the surface connected in the opposite side of the edge. Based on the magnitudes of the relation values in the attributed graph, all surfaces are classified into either occluding or occluded ones and grouped as a node set. The top object is selected as the result of the merging process of the node sets. The experimental results have shown that the proposed algorithm efficiently separates the top object in the various images of object stacks, with the time complexity of O(n) where n is the number of edges in the image. © Springer-Verlag Berlin Heidelberg 2006.