[GRASS-user] v.what.rast - solved

GRASS GRASS user
1

Hello list,

thanks to Micha Silver and Helmut Kudrnovsky, the problem ist solved. I did not set g.region prior to using v.what.rast. Seems to be a typical non-Grass-Professional mistake. Now it works fine.

But to be honest, I do not really understand what it is good for. When the raster image and the points to be updated share the same Grass location and CRS, why do I have to set a region in addition?

Best regards and thanks again, Uwe

2

Hei Uwe,

It is unfortunately not obvious from the very beginning, but actually one of the nice features of GRASS GIS.

No need to “clip” any data. You can easily operate on any subset of your data and all data will be cleanly aligned even if the extent of on layer changes….

Once you are used to it you will enjoy it.

Cheers

Stefan

···

From: grass-user grass-user-bounces@lists.osgeo.org On Behalf Of Uwe Fischer
Sent: fredag 29. mai 2020 08:42
To: grass-user@lists.osgeo.org
Subject: [GRASS-user] v.what.rast - solved

Hello list,

thanks to Micha Silver and Helmut Kudrnovsky, the problem ist solved. I did not set g.region prior to using v.what.rast. Seems to be a typical non-Grass-Professional mistake. Now it works fine.

But to be honest, I do not really understand what it is good for. When the raster image and the points to be updated share the same Grass location and CRS, why do I have to set a region in addition?

Best regards and thanks again, Uwe

3
···

On 29/05/2020 9:42, Uwe Fischer wrote:

Hello list,

thanks to Micha Silver and Helmut Kudrnovsky, the problem ist solved. I did not set g.region prior to using v.what.rast. Seems to be a typical non-Grass-Professional mistake. Now it works fine.

But to be honest, I do not really understand what it is good for. When the raster image and the points to be updated share the same Grass location and CRS, why do I have to set a region in addition?

Glad you got it worked out.

The only thing I would add to Stefan’s explanation is a pointer to the GRASS wiki on region settings:

https://grasswiki.osgeo.org/wiki/Computational_region

Regards, Micha

Best regards and thanks again, Uwe

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-- 
Micha Silver
Ben Gurion Univ.
Sde Boker, Remote Sensing Lab
cell: +972-523-665918
[https://orcid.org/0000-0002-1128-1325](https://orcid.org/0000-0002-1128-1325)
4

On 29/05/20 10:09, Micha Silver wrote:

On 29/05/2020 9:42, Uwe Fischer wrote:

Hello list,

thanks to Micha Silver and Helmut Kudrnovsky, the problem ist solved. I did not set g.region prior to using v.what.rast. Seems to be a typical non-Grass-Professional mistake. Now it works fine.

But to be honest, I do not really understand what it is good for. When the raster image and the points to be updated share the same Grass location and CRS, why do I have to set a region in addition?

Glad you got it worked out.

The only thing I would add to Stefan's explanation is a pointer to the GRASS wiki on region settings:

https://grasswiki.osgeo.org/wiki/Computational_region

Although I am a huge fan and promotor of the computational region concept, I actually agree with Uwe that it is debatable whether in the specific cas of v.what.rast this should be the default behavior. It is a bit counter-intuitive. In any case, it should be clearly and explicitly documented in the man page.

Uwe, would you mind posting an issue on this in github [1] ?

Moritz

[1] https://github.com/OSGeo/grass/issues