Steve replied to my email. Here's what he had to say: "I've run into this problem with RayDream before. The reason it's happening is that when you perform a boolean function in RayDream, the facet winding order gets all mixed up (RayDream does not take care to be sure the facets are all facing the right way after the operation.) Winding order is what UVMapper uses to determine which way a facet is facing and where it should be mapped when splitting an object using planar or box mapping. If the winding order is inconsistent, the results in UVMapper will probably not be what you expect. This problem is a little more apparent if you do a box map and split the box into 6 sides (the default setting.) I've been thinking about adding a feature to UVMapper that will run through all the facets in a model and guarantee that the winding order is consistent (to help when other programs don't seem to care about this) but haven't had the time yet. Hopefully before long I can get this done." So, it appears that there is no solution to this problem at present using UVM with Ray Dream. I had planned on using RD to create a complex interior room with elaborate texture mapping, but, if I can't solve this problem, I might as well put a hold on it until Steve makes the change he mentioned. Thanks for your time people. If anyone has any more ideas, I'd appreciate it.