Modeling terrain: Displacement map + color texture?

I am modeling terrain for 3D printing in Shapeway’s full color sandstone. Starting from the basic shape, I would like to add some displacement and texture, say little pieces of rock and some grass patches.

What is a good source for a displacement map + color texture?

What I found in the meantime: Surface Mimic

You could make your own:
Photosculpt http://photosculpt.net/
Photoscan http://www.agisoft.com/

Agisoft did have a free application called Stereoscan that was similar to Photosculpt. I believe it is now available as part of Photoscan.

Thanks for the suggestions, @cdordoni. I already found Photosculpt, but I’m not really interested in making the texture myself. I prefer something of high quality that I can just use.

In terms of detail quality in the final model the displacement map will likely not be the limiting factor but the 3D printing method itself. “Full color sandstone” is just a fancy name for a gypsum printer – the samples provided on the Shapeways site should give an idea of the surface /color detail to expect. The two cartoony models in the middle work pretty well, they consist of cleanly separated parts. Smaller detail and more subtle transitions will likely not appear, unless you print at large scale.

With high quality I don’t mean high resolution. I am fully aware of the limits of the printing process.

Well, you might consider then, that most of us can’t read thoughts.
Resolution certainly is the key feature of the surface mimic maps you mentioned.