The Clean Earth overlays replace the default Google Earth textures at high altitudes for the entire Earth. Instead of seeing inconsistent strips of different aerial/satellite photography that look very unrealistic, you can now see a nice clean natural looking Earth surface. The Clean Earth overlays use hill shading to exaggerate the vertical elevations of the Earth’s surface, which highlights hills, valleys and mountains much more than is possible with the default Google Earth surface. As you zoom in close to the Earth, the Clean Earth overlays will automatically fade away, allowing the default Google Earth surface to become visible.
The Clean Earth textures were created by combining NASA’s Blue Marble textures with global elevation/bathymetric data created by the Scripps Institution of Oceanography, which is derived from from the Space Shuttle’s SRTM mission and other sources.
There are two versions of the Clean Earth overlays. The High Resolution version provides a much greater level of detail and will be visible at lower altitudes than the Low Resolution version. The Low Resolution version (on by default) has less detail, but will load much faster, especially on older machines with slower internet connections.
I will also be adding Ultra-High resolution textures to certain areas of the Earth that will be based on much more detailed elevation data. If you have any suggestions for areas that would be interesting to see in Ultra-High detail, post a comment.