DMM, you're explanation of the filter graph was perfect. I think I understand completely now. Many thanks for telling it in a simple, straightforward way! After adjusting my step a few times, got perfect results. In fact, now that I understand, I'm looking forward to feathering at the edges. Thanks again. Stewart, I'm at a loss for any more ideas on what's going wrong at your end. I'm using tga for my maps (old habit), but don't think jpg would cause the problem. If you want to upload your scene, I'll try it on my machine and see what there is to see.