To make realistic Simcity 4 terrain, like the one in Simcity 4 Europa Terrain, I used this process:

  1. Create a multiple layered Photoshop or Paint Shop Pro file as described in this article, which is used to seperate the difference between land and water.
  2. Use a big solid brush tool, at land layer (about light=84) to create the basic filled land outlines. Blur this land outline to soften the land.
  3. Use a huge, soft brush tool on a mostly transparent layer to add some basic hills in the land (and the ocean).
  4. Create another layer. Use a semi-opaque solid brush tool, at the top land layer (light=255), to create the outlines of mountain ranges. By using semi-opaque, it will draw below 255, and ranges can accumulate on top of each other to increase in height.
  5. Blur these lines to soften the mountains up.
  6. Use Paint Shop Pro’s retouch tool, using it on Smudge, very softly (0% hardness) and very gritty (40-70% density). Use this smudge to create the semi-mountains between land and mountain ranges. With some practice you can get the land looking fairly realistic (as seen in Simcity 4 Europa Terrain).
  7. As this is on another layer, you can reduce the opacity of the layer to reduce the effects of the mountains.
  8. To make it easier, create multiple mountain ranges per file, so it’s easier to revert changes and adjust the effects of each layer.
  9. You can use another huge, soft brush tool to add additional hill/valley effects in the image.

I don’t feel like creating a step-by-step guide to this process, but this creation allows for fairly realistic-looking terrain images which you can import into Simcity 4. Enjoy!