Great idea Isomage. I can see me using this. Repped. Maybe you need to be more abstract to represent alien terrain. Simple things like your triangle for mountains, a scribble blob for vegetation, the traditional 3 stalks for swamps, a couple of dunes for desert...

Alien colour can be a problem. Again, I'd go with simplistic representation (though I'm probably in the minority here amongst the artistic types) with maybe just two or three colours, khaki for land, bluish-purple for 'sea' and maybe a greyish-brown for arid/barren areas.
Just my two credits.