I decided to return to the fake rocks shader after messing with it a bit a while ago, and the best I can get is only some of the rocks look natural. I use a power fractal for the surface input of the shader, and then go from there. They just don't look real, and I can't get an image shader to work for the fake rocks either. Any good pointers? I searched the forum for threads, but they weren't too helpful.
Try a redirect shader with power fractal inputs of differing colours and low displacement... and really small scale
An image shader won't work right (as I'm sure you know) because the individual rocks don't have UV coordinates, and other projection schemes will only look acceptable on subsets of the whole population. (Depending on the situation, this might be ok. I've done one set of rocks with a granite image texture that came out really cool. Not too realistic, but cool.)
I've attached a clip file with a stones shader, a color shader and fractal breakup. It's not great but it looks ok.
I use the image shader all the time with fake rocks. You don't use the Object UV projection though, the Plan Y works the best unless the rocks are on a really steep slope, in that case you would use the Side X or Z projections.
Make sure the Repeat x and Repeat y boxes are checked in the "Flip, Repeat" tab.
When you choose the image it helps if it is seamless. There is a free program called Gentica Viewer ,it can make some pretty cool textures that you can vary for different scenes, below is the site.
http://www.spiralgraphics.biz/packs/index.htm
The last thing you will have to do is scale the image so it works with the image (the default of 1 is too small)
I usually start with 10 of course the size of the image will determine allot especially if you use an image that is small in size i.e.. 256x256 or lower. When you scale these up you just scale up the pixels, which looks bad.
Hope this helps. :)
I do the same as sonshine777.