@dark coder: lol!
if i was going to do this, the method i'd have for changing between a sphere, to the matrix landscape, would be to fly through some clouds... while you're in them, you've got little visability, then swap the matrix and sphere over, no one notices the difference
I'm not going to go into too much detail about posible ways of doing this, but you could use a greyscale heightmap to store your landscape data, and then plot your player's position on the planet's surface with reference to the bitmap, then look at the pixels around you, and use the pixel's values to create your landscapes height.
but remember what darkcoder says here... if you're planning an entire planet... and then alien planets too... think again, it aint gonna happen
I don't have a sig, live with it.