An innovative solution to the interposition problem in Augmented Reality is presented. The realistic and physically consistent embedding of a 3D virtual object (3DVO) into a real scene is accomplished by considering it as a set of points or vertices. Our method deals with stereoscopic views of an unstructured and unknown real scene and avoids explicit 3D reconstruction. Instead, we rely on local stereo matching to decide whether each vertex should be visible or not. After a geometrical analysis of the problem, we detail our solution and present preliminary results of interposition for 3DVOs and real scenes.