View Full Version : Creating grayscale heightmaps

11-22-2010, 03:54 PM
Ok, so I've been working on This (http://www.cartographersguild.com/showthread.php?12556-Sandboxing-it) just playing around. With the suggestions listed, I began trying to tweak it into something more realistic with foothills and plains. So I started examining real geological/geographical data and relief maps. My problem is this: I can't seem to recreate something that looks quite right compared to a DEM (digital elevation model) map. The DEMs render up with some wonderful smooth plains, foothills, and mountains.

I've used several tutorials from the forums here as well as around the net that I've dug up. I've been able to make good looking very rough terrain, high mountains and rocky land. I am however having a devil of a time trying to create anything that looks more natural with mountains, foothills, and plains. I have an idea for a map that I'd like to create next, but I really need some help getting over this hump before I can start much on that idea. I suspect that my attempts are falling short in some way that I'm just not seeing, but I could really use some extra eyes.

So, anyone have any ideas to help me out here? I've tried several methods in photoshop and I'm coming up dry on ideas.

Thanks for the help!

Here's the original height map for the linked thread.


11-22-2010, 07:47 PM
To truly recreate a grayscale heightmap in a raster program you need to spend a long time tweaking the colors of your terrain with minute adjustments in color. Tiny tiny adjustments that have almost no visual effect. Therefore that makes it hard to do. When I was really obsessive about such things I'd import my grayscale into Terragen, have that render the image, then go back to my grayscale and tweak for a while, then repeat. It got to be too time-consuming and really helped cure my obsessiveness.

11-23-2010, 01:45 AM
The key to a plausible heightmap is, in my opinion, erosional effects. There are several ways to go about getting the type of erosion you're after. The most direct way is to pick DEMs with the types of features you want and paste together those pieces in Photoshop (or GIMP or what have you), being careful to keep the rivers aligned. If you have a grayscale image editor that can do Poisson blending then it's a little easier still because you'll get good blends.

I'm way too lazy for that, though. I use Wilbur to synthesize erosional effects on a preexisting heightfield. The attached image is the 15 minute fiddling with fill, erosion, and exponent as described at http://www.ridgenet.net/~jslayton/FunWithWilburVol1/index.html (in case you're interested in the process more than the results).

The first image is the sea mask, the second one is an eroded version of your original heightfield with some exponential operator to give more in the way of plains, the third is a river map, and the final one is a simple altitude-shaded image with a river overlay.

11-25-2010, 06:56 PM
...a grayscale image editor that can do Poisson blending...

That's a new one for me. Can you provide any references?

-Rob A>

11-25-2010, 11:22 PM
http://portal.acm.org/citation.cfm?id=882269 is the reference for the classic paper on the subject. http://www.cs.unc.edu/~lazebnik/research/fall08/jia_pan.pdf has a presentation on the information from the paper.

This technique is usually described as "seamless blending" or "seamless cloning" in typical image editing tools.

Howard Zhou's paper ( http://www.howardzzh.com/research/terrain/ ) uses a combination of graph cuts and Poisson blending to path together exemplars to match an existing pattern. There are filters available for World Machine that implement this paper.

12-02-2010, 06:47 PM
I'm really looking forward to the next version of Wilbur all of the sudden.

01-15-2011, 02:49 PM
thats kinda crazy