All images are free from any copyright - you can use them for whetever you desire.
for examle [1] is just great for creating new maps.
there are also some hi-res images like this mars-one: [2] (downloadable as 23444 x 23377 pixel in tif or jpg-format (548.1mb resp. 47.26mb))
or this map ( [3] ) from earth woul make (mirrored at bottom of course) a great challange. the colors are actually heighmaps (just make the sea black and convert it to grayscale .. thats it).
what are u waiting for? i can't do all alone
