[R-sig-Geo] Mapping contours from jpg map
Johan Van de Wauw
johan.vandewauw at gmail.com
Fri Jul 8 09:33:53 CEST 2011
Apart from grass gis, you can also do this in saga gis, or run this
through RSAGA. Since it seems you have to do this only once, it would
be much easier to just use the GUI.
1) Open your shapefile
2) run the module grid\shapes to grid (choose a reasonable cell size)
3) run the module grid\close gaps (you now have a altitude grid)
4) run the module terrain analysis\morphometry\slope,aspect... (you
now have a slope grid)
5) you could now overlay your points, or do that in R.
On Thu, Jul 7, 2011 at 6:25 PM, Sarah Papworth
<sarah.papworth06 at imperial.ac.uk> wrote:
> Dear all,
> I have a jpg map of altitudinal contours in my study area which I
> would like to map and use in R to calculate the altitude and slope of
> GPS coordinates.
> So far, I have painstakingly traced these contours in ArcMap to create
> a shapefile (of polylines) with altitude. I have now imported this
> file shapefile into R.
> What I would like to do is turn it into a raster of slope and
> altitude, but I can't seem to find any method of doing this in the
> online R help archives. Does anyone have any idea which package I
> should be using, or perhaps if it is even possible to turn this type
> of shapefile into a raster?
> Thanks in advance!
> Imperial College London
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> R-sig-Geo at r-project.org
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