Features from DEM anyone?

[Martin Ameskamp]

Hello out there!

We (Computing Dept. and Soil Science Dept. at Kiel Uni) are working on 
three-dimensional soil modeling (rule based, fuzzy, ... the lot :-)
We have elevation information (contours, raster) which we handle using GRASS.
Apart from obtaining drainage information (using the 'watershed' module) we
would also like to extract 'features' from the DEM, i.e. one or both of the
following:
- Classify each point in the raster as slope, ridge, saddle, ...
  This is pretty straightforward if you simply take a 3x3 matrix, but if you 
  want better results, things like smoothing, different scales, etc. come
  into it.
- something along the lines of the 'watershed' basin output: divide the
  raster into areas of common morphology: hills, valleys, slopes, ridges,...
  
And now, the obvious question: has anyone done this already? In GRASS, maybe?
If so, are you willing to share experiences and/or programs?
I think it wouldn't be too hard to implement some rough version of vectorial
slope classification (there are a couple of good papers around) but I guess
it would require quite a bit of work to come up with a reasonable robust
and adaptable program and before we (actually I'm the only programmer in this
project :-() reinvent the wheel...

Any information at all welcome!

Thanks in advance,  Martin
--
Martin Ameskamp, Kiel University, Germany
Fax: ++49 431 8804054, Voice: ++49 431 8804474, 
email: ma at informatik.uni-kiel.dbp.de