My bmp names are prefixed with

I think you can best try to compile from the DOS prompt. Then you can see any error message that appears.From this source I notice a few things:1. If you use the ADDCAT command the polygon can best be on the ground level and not 0.1 meter above.2. There is still crash detection in the code, you can better export ground polygons without crash detection.

Did as you said, I got a successful compile but still get "some minor" shadow degradation in spot plane view....however, as you suggested, the polygon behaves as it should. Thanks for all the input.

Bob B, is there any reason why 1024 x 1024 polygons can't be used to do this? Or are you already doing it at a 1024 level?

Not sure, John. It might be worth a try...it seems I did this once and chose to limit myself to 512, but I don't remember why (old age). My suspicion is that 1024s begin to slow texture refresh, but I could be wrong. Congrats on moving forward with this style of polys, I have to believe you'll be happier once its comfortable to you.B

For the grid I made I used textures of 1024x1024, that way each sqaure covers 1x1 km roughly. The airport I used this for (Schiphol) is rather big, but I did not notice a big framerate hit. In total about 50 textures are used for the grid.