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Calculation of geographical slope
3 messages · May, Roel, Roger Bivand, Tomislav Hengl
2 days later
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 [[alternative HTML version deleted]]
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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
5 days later
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 [[alternative HTML version deleted]]
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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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