Some of you may already have seen this one on renderosity today.
This image was a study to obtain realistic cracks on rocks/fake stones and was also an exercise for micro-displacement on the soil.
There are a few grey "patches" on the soil which are actually fake stones which are displaced downwards. Finding the right displacement value for all fake stones is very hard.
I've also used a combination of GI and fill lights with a customised 9 sunlight-array to create softer shadows.
Rendered with the unregistered version, can't remember rendertime anymore, about 2,5h I guess.
Rendersettings:
Detail: 0.85
AA: 3
GI: 3/3
Gamma: 1.5
Contrast: 0.325
Raytracing on (unnecessary, forgot to switch off)
As some of you already may have read here on the forums there's a thread going on about how to create these cracks on rock/fake stones.
You can find it here:
http://forums.planetside.co.uk/index.php?topic=1939.msg19180#msg19180Postwork (crappy DOF) in Photoshop CS2.
(don't know if you read this Ben, but I've been trying to use your depth-map technique and had some troubles creating the mask due to the fake stones (I think)).
Greetings,
Martin