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?