Realistic heightmaps from coastlines & basic mountain positions- GIMP + Wilbur

[Omnigeek6]

So I've been making a map of a large region of a continent - the land of Totallynotmedievaleurope - starting with a hand-drawn coastline and locations of major mountain ranges.

Basically, the current map is color-coded with sea, lowlands, highlands, and three heights of mountains.

The problem is, I can't figure out how to turn this rough map into a realistic heightmap.

I really like the results from this tutorial: http://www.cartographersguild.com/tu...mp-wilbur.html
but I can't get the mountain chunks to blend together properly, and they don't match the shapes I came up with beforehand very well.

Are there any other good methods for generating a heightmap from this type of map?

[waldronate]

http://www.cartographersguild.com/ma...und-lands.html has a tutorial that outlines a process that will get you something like the image below. The image below is a variant on the described process, in that I started with a downsampled 375x500 image to do the basic processing quickly and then upsampled back to the original resolution and did a finishing pass with incise flow and precipiton erosion. I didn't bother with fancy coloring or touchup in Photoshop. I also added a few bits of linear gradient to force the river direction to align better with the landforms.