[R-sig-Geo] Calculation of geographical slope

[Tomislav Hengl]

If you are windows user you might also consider using RSAGA with probably
has much richer geomorphometric analysis possibilities than GRASS.

https://stat.ethz.ch/pipermail/r-sig-geo/2008-January/003078.html

> On Wed, 7 May 2008, May, Roel wrote:
>
>> Hi all,
>>
>> Does anyone know if there exists a function in R that can calculate
>> geographical slope and aspect (i.e. like elevational slope/aspect) on
>> grid values?
>
> I'd suggest pushing the DEM out to GRASS, and using the module there. It
> could be done by creating new columns in a SpatialGridDataFrame for the
> eight neighbours and just doing the math - Zevenbergen and Thorne (1987)
> algorithm (for a reasonable sized DEM), but we don't have a function for
> grid shifting yet, contributions welcome!
>
> Roger
>
>> I've looked around on the R-sites but could not find anything on this.
>> I hope can help a simple soul...
>>
>> Cheers, Roel
>>
>> Roel May
>> Norwegian Institute for Nature Research
>> Tungasletta 2, NO-7089 Trondheim
>> Norway
>>
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>>
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>
> --
> 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
>
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