[R-sig-Geo] projection

Tomislav Hengl hengl at spatial-analyst.net
Thu May 20 20:36:55 CEST 2010


It is a pity that people that have provided this data did not attach  
any metadata (see for example the simple metadata format I used to  
prepare worldmaps e.g.  
[http://spatial-analyst.net/worldmaps/globedem.rdc]).

My favorite places to look for correct proj4 strings (i.e. projection  
parameters) are [http://spatialreference.org] and  
[http://epsg-registry.org]. In this case I get multiple matches e.g.:

[http://spatialreference.org/ref/?search=ED+1950+Lambert+Conformal+Conic]

which means that you either need to test each one (reproject to latlon  
coordinates and then display in Google Earth). Or you need to contact  
the people that gave you this file and check with them how did they  
generate that map.

Otherwise, why break head? You can also obtain the SRTM blocks  
yourself and rebuild (mosaic) the map for the area of interest:

[http://srtm.csi.cgiar.org/SELECTION/inputCoord.asp]

In fact, this is probably the best recommendation that I can give.

HTH

T. Hengl
http://home.medewerker.uva.nl/t.hengl/


Quoting "Heuvelink, Gerard" <Gerard.Heuvelink at wur.nl>:
> Dear list,
>
> I hope someone can help me with the following.
>
> I have an SRTM DEM of Turkey in the "ED 1950 Lambert Conformal Conic"
> projection system.
>
> However, I do not know how this is referred to in R. For example, I
> might load the dem as:
>
> DEM = readGDAL("srtm_5km_ascii.txt")
>
> Next I will want to let know what projection it is by issuing:
>
> proj4string(DEM) = XXXXXXXXXXX
>
> What do I write for XXXXXXXX?
>
> Thanks, Gerard
>
>
> Gerard B.M. Heuvelink
> Environmental Sciences Group
> Wageningen University and Research Centre
> P.O. Box 47
> 6700 AA Wageningen
> The Netherlands
>
> tel +31 317 486538 Mon Tue
> tel +31 317 482716 Wed Thu Fri
>
> email gerard.heuvelink at wur.nl <mailto:gerard.heuvelink at wur.nl>
> http://www.lad.wur.nl/UK/ <http://www.lad.wur.nl/UK/>
> http://www.alterra.wur.nl/NL/onderzoek/Werkveld+Bodem/TBGE/Gerard+Heuvel
> ink/
> <http://www.alterra.wur.nl/NL/onderzoek/Werkveld+Bodem/TBGE/Gerard+Heuve
> link/>
>
>
>
>
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>
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