poser may be able to use depth map shadows on an isolated small object (a very small scene), but it's tricky.  the black square corresponds to the shadowmap of the depth-mapped infinite lite.  thus the black square can be scaled and/or moved by switching to the pertinent shadowcam, allowing the small object to be illuminated by scaling down and moving the shadowmap.  to get the depth-mapped shadow, it may be necessary to edit the pz3 file for the shadow blur radius, which, if fixed at >= 1.0, is larger than the object's shadow. 

however, if anybody was wondering whether depth-mapped shadows are better than ray-traced shadows, in versions of poser prior to 8, there is at least one instance in which the ray-traced shadow is required.