[GRASS-user] Problem with r.out.ascii

[Hamish]

PikoBoZ wrote:
> Im trying to use the r.out.ascii command but it fails
> Got an existing mapset, with some elevation rasters in it (.tiff
> converted in grass raster)
> I'd like to extract the xyz values of a DEM to txt file
> I use this syntax in the grass shell:
> [code]
> r.out.ascii input=mnt output=testmnt.txt
> [/code]
> testmnt.txt is created and the header is written,but the x,y,z values
> are
> missing, only stars appear in it, like this:
> [code]
> north: 2787570
> south: 1546950
> east: 1284500
> west: -47544.1
> rows: 931
> cols: 999
> * * * * * * * * * * * * *
> * * * * * * * * * * * * *
> * * * * * * * * * * * * *
> [/code]
> Is anybody understands what happens?

r.out.ascii exports a rectangular array of values (like for a
spreadsheet with x & y axes), in your above example 931x999 cells. The
"*"s represent NULL data.

Raster ops. work on the current zoom region. see the g.region module.
e.g. set to the region to the exact extent of the raster map with:
 g.region rast=mnt

> Does a r.out.xyz command exist?  or any other way to get x,y,z values
> from a raster?

yes, there is a r.out.xyz, but only in grass 6.3.
 http://grass.ibiblio.org/grass63/manuals/html63_user/r.out.xyz.html
 http://trac.osgeo.org/grass/browser/grass/trunk/scripts/r.out.xyz

but that is just a more obvious alias for "r.stats -1gn", so for GRASS
6.2 you can use that.



Hamish



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