[GRASS-user] GRASS 6.4 How to extract point-values from multiple rasters
markus.metz.giswork at gmail.com
Sat Apr 6 13:34:46 PDT 2013
On Sat, Apr 6, 2013 at 1:11 PM, Tim Michelsen
<timmichelsen at gmx-topmail.de> wrote:
>>>> I have to extract isolated value from several raster.
> Yesterday I had the same task to solve:
> have a vector with some sampling points and wanting to insert values
> from 2 raster layers to the table.
>>> The GRASS module r.what  extracts raster values at a
>>> given location. As input you need to give the name of the
>>> raster map and the coordinates as east,north
>>>  http://grass.osgeo.org/grass64/manuals/r.what.html
>> note that r.what can take multiple rasters and multiple point-
>> values as input, all in one pass, to make a table.
> I do not understand why r.what should be of help here.
r.what would not help here, but for the original question because
there a vector map was not mentioned.
> r.what  just prints out.
> Isn't the right tool v.sample ?
r.what extracts values from one or more raster maps at locations given
v.what.rast uploads raster values at positions of vector points to the table.
v.rast.stats calculates univariate statistics from a raster map based
on vector areas (polygons) and uploads statistics to new attribute
> But this tool works in a way the user would not expect it:
> Now, the problem is with v.sample:
> 1) it just accepts 1 input raster only.
> 2) it creates a new vector with a totally new table instead of updating
> the attribute table of the input vector with the raster values
> A note to 2): Such a procedure is implemented in v.rast.stats.
> What do the GRASS devs think about the items 1) & 2)?
> Is it a legitimate enhancement?
> Kind regards,
>  http://grass.osgeo.org/grass64/manuals/r.what.html
>  http://grass.osgeo.org/grass64/manuals/v.sample.html
>  http://grass.osgeo.org/grass64/manuals/v.rast.stats.html
> grass-user mailing list
> grass-user at lists.osgeo.org
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