[GRASSLIST:4362] Re: concave slopes

[Thorsten Behrens]

Hi Temiz,
the easiest way to check it out is to drape the curvature map
over a DEM. The problem is that different authors use different
signs to calculate curvature... For example Zevenbergen und Thorne 
(1987) use "C = -2(a + b) * 100" to calculate mean curvature. This
formula is implemented in ArcView/ArcInfo. Moore et al. use 
"C = 2(a + b) * 100", which is implemeted in Tapes-G (I guess).
Another problem to solve is the classifcation of the curvature
map. Try something like: "-min - -0.05","-0.05 - 0.05","0.05 - max".

Shary (2001) shows a set of 15 different surface derivates. Some
others can be found in Wood (1996) and in Wilson and Gallant (2001).
All together I found 23 differnt "curvatures".

If you need the references let me know.

Hope this helps
Thorsten