[GRASS-user] cut raster

GRASS GRASS user
1

Hi everybody! I’m a beginner with GRASS… I have a lot of questions. Now I need to cut out an area from a satellite image according a relevant vector object from digital map. I need to cut out a building from satellite image, that I have as a vector object, and save it to the new raster map (only one building). Or may be it’s possible to cut out an area from a satellite image using coordinates from vector object.

2

Hi Sofina,

The way I normally do this is first, convert the vetor to raster
(v.to.rast). Then I transform the converted newlly created raster to a
mask (r.mask) and, using r.mapcalc, clip the satellite image. Don't
forget to latter remove the raster mask.

The commands performed would be something like this:
v.to.rast input=building_vector output=build_raster
r.mask build_raster
r.mapcalc
clipped_sat = satellite_image
r.mask -r

@ Grass List.
I can't recall if there is an easier way to do this... Maybe a script?
Such a simple procedure should be done easily in one step...

Cheers
Daniel

On Thu, Oct 14, 2010 at 10:16 AM, Sofina Natalia <nsofina@gmx.de> wrote:

Hi everybody! I'm a beginner with GRASS... I have a lot of questions. Now I
need to cut out an area from a satellite image according a relevant vector
object from digital map. I need to cut out a building from satellite image,
that I have as a vector object, and save it to the new raster map (only one
building). Or may be it's possible to cut out an area from a satellite image
using coordinates from vector object.

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grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

3

Daniel Victoria wrote:

Hi Sofina,

The way I normally do this is first, convert the vetor to raster
(v.to.rast). Then I transform the converted newlly created raster to a
mask (r.mask) and, using r.mapcalc, clip the satellite image. Don't
forget to latter remove the raster mask.

The commands performed would be something like this:

I would add some g.region commands:

# set region to extends and grid cell geometry of satellite raster
g.region rast=satellite_image

v.to.rast input=building_vector output=build_raster

# reduce region to non-NULL part of build_raster to reduce clipped raster size
g.region zoom=build_raster

r.mask build_raster
r.mapcalc "clipped_sat = satellite_image"
r.mask -r

Markus M

@ Grass List.
I can't recall if there is an easier way to do this... Maybe a script?
Such a simple procedure should be done easily in one step...

Cheers
Daniel

On Thu, Oct 14, 2010 at 10:16 AM, Sofina Natalia <nsofina@gmx.de> wrote:

Hi everybody! I'm a beginner with GRASS... I have a lot of questions. Now I
need to cut out an area from a satellite image according a relevant vector
object from digital map. I need to cut out a building from satellite image,
that I have as a vector object, and save it to the new raster map (only one
building). Or may be it's possible to cut out an area from a satellite image
using coordinates from vector object.

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user

_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/grass-user