Hi Kevin and all, I have enjoyed many discussions with Dr. Leslie Kay. His sonar systems, KASPA and SonicGuide, are subject to the very same inherent ambiguity for symmetric object views. This is resolved only by the user by moving or turning around to break any such symmetries. Moving or turning around is of course just another form of (manual in this case) scanning. Best wishes, Peter Meijer Seeing with Sound - The vOICe http://www.seeingwithsound.com http://www.visualprosthesis.com > wonder if it would b helpful at all to consider how the Kaspa or sonar cane > from Dr. Kay's research works. that's all real time sonic images though not > really 3d well maybe to a point. maybe someone could do some experimenting > with it and see if objects canceled out each other etc.