Hi guys, this thread is quite old now, but it fits well into my question.
I would like to know how Google Earth altitude information is measured. To make it clearer: I would like to know where this information comes from, how the satellites measure it. I presume that the altitude in Google Earth is derived from the satellite data.
The reason why I ask ist that I tried to profile a piece of land with a lot of high trees. I knew that there should be a creek with steep slopes on both sides because I had climbed down to the creek and then back up again, but I could not locate the creek with Google earth. Any of the various routes that I drew across the supposed position of the creek shows a rather gentle altitude profile with no sudden hole. The slope appears to be not more than 10-15%, the same slope as the road to our house that I walk up and down every day woithout any problem. But the slopes on both sides of the creek were so steep and high that we had do go down in serpentines and then had to search a while along the creek to find a place where to climb back up without too much difficulty. Nothing of this is shown in Google Earth profiles. But I noticed that all around the creek there were very high trees, about 60 to 100 feet high, while on the higher parts the trees were not so high. This leads me to the conclusion that the altitude information is gained with optical methods so the tree tops of the forest appear to replace the ground.
Can anybody confirm or correct this thought?