Hi Philip, also you should check out the help file where the picking process is describe in detail: http://moi3d.com/3.0/docs/moi_command_reference8.htm#flow

You don't have to do it by trial and error, you control it by clicking on specific areas on each surface and then it will match up those pick locations. You want to click close to an edge, on one side of the edge as described and illustrated in the help file.

- Michael