So... What's the trick?

Using FS Earth Tiles, I've begun playing around with making my own photo-real scenery for FS9. Once properly configured, it's a great, simple program to use. The scenery turns out great. Here's the problem. Any of you that have installed any of Gottfreid Razek's "Blue Sky" scenery, immediately know the difference between low-res and hi-res photo-real. Well, as it turns out, FS Earth Tiles is perfect for making low-res scenery, but I'm after the hi-res stuff. How do I do it?