What a nice place here ! The questions/answers system is very elegant. I have read and get some useful informations allowing me to write a little .hgt reader... I am working on C.G.I and create 3d images and visual FX. Then, writing this script bring me to be aware of my huge lack of knowledge about geographic science.
During my tests, I noted a difference between the terrain made from a specific hgt tile and the actual satellite photo ( googlemap ref) of the same area.
You can watch my terrain generation result
The blue part is MY water level ( 0 meter in the hgt file). But if you watch the same zone in googlemap, if the overall look is good, you note big difference in the coastline.
Why that difference? Is the sea level above 0.0?