Check out my City Designer 3 tutorials. See my fantasy (city) maps in this thread.
Gandwarf has fallen into shadow...
Yeah that avatar is the best. Certainly now that Arcana changed from the Black Metal god... hah.
Right, well I am no Gimp expert but I think it can render a filter of clouds and then you just do a contrast stretch to black and white and that gets you a random shape. There is also my free app instant Islands which does this sort of thing...
http://www.viewing.ltd.uk/cgi-bin/vi...nstant_islands
The brute force way is to create a small - say 32x32 bit of greyscale noise map and then upsample it to 64x64, smooth it slightly and then add a little bit more noise and then upsample to 128x128 and keep repeating that until its big enough. You can tweak it at any stage by hinting it lighter or darker as required.
In Gimp there is also supposed to be some kind of render random map mode too where it paints the land in green and the sea in blue too. All with one click.
To glow the border the usual method is to take the land and mega blur it. Then add back in the land again. So get the land in the glow color with sea being the same as the normal land map. Mega blur it and then select just the land from the original and paste over the blurred one at the same coords as it was in before.
I'm not sure I quite understand how to glow the borders like you described, but I'm guessing this mega blur thing yields bolder edges than other blurs and I need to use layers and opacity?
Anyway, pertaining to the terrain stuff, the issue I'm having isn't generating terrain - I'm already able to do that easily with Fractal Mapper 8. It's generating topographic lines (not shapes) for rivers and borders in GIMP or Photoshop.
I was waiting for something so I knocked off a few images. This is for the rand terrain. Ok so its quick and dirty and the amounts of noise need to be tweaked down a bit cos its a bit over the top. I'll do the glow in a mo...
Heres quickie steps. Start with some terrain, generate glow colored version, blur it a lot, select original land and paste on top. Again, this is my super quick attempt and probably needs more finesse but thats it basically.