Can anybody explain how the altitude information in Google Earth is generated? I have created various routes over a forest area where there is indeed a creek about 50-60 ft lower than the plain nearby, with very steep slopes on both sides that make it very difficult to get to the creek and then back to the upper level. I have been down there, so I know it. But the altitude profiles created with Google Earth don't show such a hole, they show a steady slope of about 10-15%, just like the road leading to our hose which I am walking every day without any problem.
I noticed that the tree tops in the creek area were much higher than elsewhere and had nearly the same altidude as the higher surroundings. This makes me think that the altitude information is created from optical data from the tree tops and not from the real ground.
Or do these data have such a low resolution that a 40 m wide hole does not create a bump in the profile? The length of the profiles is around 250 m (750 ft).
Can anyone enlighten me?