[GRASSLIST:10826] Re: other methods for calculate profile and plan curvature

[Roger Bivand]

On Wed, 8 Mar 2006, Carlos "Guâno" Grohmann wrote:

> Hello all.
> 
> I have just resampled a SRTM DEM using krigging (in R) and did the
> same with RST. The maps are very similar. When I resampled
> (interpolated) the DEM with RST, I can choose to derive maps for plan
> and tangencial curvature (among others) at the same time, and so I
> did.
> For the map interpolated with krigging, I have to derive curvatures
> using r.slope.aspect.
> While the DEMs are very similar, derivative maps don't. Curvature maps
> calculated with r.slope.aspect have lots of artifacts, while those
> from rst are much more smooth.
> 
> So, I want to ask how I can calculate these curvatures in another way
> (r.mapcalc?)? I'd like to use the same method over both DEMs.

You can use the Zevenbergen and Thorne (1987) recipe given by Burrough and 
McDonnell, 1998, p. 191 - do you have access to that? You do r.mapcalc 
using raster array indexing to make 8 shifted arrays, then more r.mapcalc 
to get slope, aspect, plan and profile curvature.

Roger


> 
> thanks
> 
> Carlos
> 
> 
> --
> +-----------------------------------------------------------+
>               Carlos Henrique Grohmann - Guano
>   Geologist M.Sc  - Doctorate Student at IGc-USP - Brazil
> Linux User #89721  - carlos dot grohmann at gmail dot com
> +-----------------------------------------------------------+
> _________________
> "Good morning, doctors. I have taken the liberty of removing Windows
> 95 from my hard drive."
> --The winning entry in a "What were HAL's first words" contest judged
> by 2001: A SPACE ODYSSEY creator Arthur C. Clarke
> 

-- 
Roger Bivand
Economic Geography Section, Department of Economics, Norwegian School of
Economics and Business Administration, Helleveien 30, N-5045 Bergen,
Norway. voice: +47 55 95 93 55; fax +47 55 95 95 43
e-mail: Roger.Bivand at nhh.no