Google Overlay...

Anybody got a grip on how high above the terrain the overlay actually 'floats' ??
I make it about 12 or 13 feet above... which would put it at around 4 meters above the terrain. I also noticed that, as the grade increases, so does the overlay. Seemingly staying at approximately the same 4 meters above terrain over distance. Is the overlay following some form of topographical data. Or... is the overlay making mathematical adjustments based on the existing terrain and disregarding the severe changes in grade.
In an urban environment, with tall structures, the terrain seems to be interpret them as rather large mounds. Consequently, these mounds 'poke' trough the overlay. After re-grading said mounds to some point (4 meters+/-) below the overlay, the resulting terrain appears more like what I know the true topography to be.
Just curious... anybody got an opinion on this??
I make it about 12 or 13 feet above... which would put it at around 4 meters above the terrain. I also noticed that, as the grade increases, so does the overlay. Seemingly staying at approximately the same 4 meters above terrain over distance. Is the overlay following some form of topographical data. Or... is the overlay making mathematical adjustments based on the existing terrain and disregarding the severe changes in grade.
In an urban environment, with tall structures, the terrain seems to be interpret them as rather large mounds. Consequently, these mounds 'poke' trough the overlay. After re-grading said mounds to some point (4 meters+/-) below the overlay, the resulting terrain appears more like what I know the true topography to be.
Just curious... anybody got an opinion on this??