That's fantastic (and I'm really glad you got the shadows working, they help A LOT).
This is the slopes graphics I'm hoping to use BTW http://goblinart.pl/files/DF/slopes.jpg
Can you explain a bit about this image?
You know, while trying to make a mock-up of this system in use, I realized it wouldn't work! Back to the drawing board...
EDIT: okay, here we go.
Now I do realize this is a bit of a huge change from what the DF display is currently about, but I also believe it makes the terrain display much clearer.
Apart from your typical occlusion, here's what needs to be done (most of it by the tileset maker):
-flat ground needs to be kept around 75% brightness
-ramps facing south need to be at 100% brightness
-ramps facing west and east - 40% and 60% (could both be 50% but it's better to differentiate)
-ramps facing north - 25%
In the following rant, I'm only talking about terrain (ground, ramps, walls, constructions etc.). Objects and creatures are a completely different subject.
I believe it's a huge distraction right now that neighbouring flat ground tiles can vary in brightness greatly. Now that we're nearing full graphics support (thanks to you and Warmist), it is imperative that both brightness and saturation are taken into account to help differentiate between flat ground, ramps and walls.
While the material (and the presence of grass) can currently GREATLY influence the brightness of a tile, I believe they should be kept close to the values listed above.
Here's my proposal on a partial set of grassy ramp icons + the normal flat ground in the middle (some additional ramp icons might be necessary for the more complex "ramp neighbourhood" situations).
It doesn't include any special graphics, the only thing that changes is the brightness (value) of the texture. But in the mockup above you can see that it provides a very clear representation of the terrain.
Creature and object icons are a bit of a problem with this, because the ground beneath them doesn't get displayed. For that reason, their tile background should be kept close to the flat ground brightness - see:
http://goblinart.pl/upload/mockup3.jpg