[R-sig-Geo] Calculation of geographical slope
Roger.Bivand at nhh.no
Fri May 9 16:52:15 CEST 2008
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!
> 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
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