Here is a tip for creating high resolution terrain over a large area, importing from GE to SketchUp. I discovered this method while making the Sundance 06 file.

First, lay out the entire area you want by importing it from GE. You will notice that the resolution is fairly low.

Then delete the imported terrain and flat image, and reimport smaller tiles showing pieces of the large area. These will tile at higher resolution than the original coverage, positioned exactly where they should be.

SMcQ