[GRASS-user] merge 2 ascii-DEM/grass-DEM

GRASS GRASS user
,
1

Hi.

Just started to explore grass 6.4, and have manage to view one DEM in NVIS. I wonder how I can merge 2 or more raster-DEMs i grass? I working from QGIS with the GRASS-plugin.

2

I wonder how I can merge 2 or more raster-DEMs i grass?

r.patch ?

Creates a composite raster map layer by using known category values from one
(or more) map layer(s) to fill in areas of "no data" in another map layer.
http://grass.osgeo.org/grass64/manuals/r.patch.html

another nice way, build a gdal virtual dataset
(http://www.gdal.org/gdal_vrttut.html) with 2 or more DEMs outside of
qgis/grass and r.external (Link GDAL supported raster file to a binary
raster map layer: http://grass.osgeo.org/grass64/manuals/r.external.html) or
r.in.gdal (Import GDAL supported raster file into a binary raster map layer:
http://grass.osgeo.org/grass64/manuals/r.in.gdal.html) the virtual raster.

HTH

-----
best regards
Helmut
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3

I think my terminology are bad. The DEMs are over different areas beside each other, but within the mapset and location, so ‘merge’ are maybe not the right terminology? Or maybe there are another way? But when I load into NVIZ I can only chose one layer, DEMs in the mapset listed…

···

2013/4/5 Helmut Kudrnovsky <hellik@web.de>

I wonder how I can merge 2 or more raster-DEMs i grass?

r.patch ?

Creates a composite raster map layer by using known category values from one
(or more) map layer(s) to fill in areas of “no data” in another map layer.
http://grass.osgeo.org/grass64/manuals/r.patch.html

another nice way, build a gdal virtual dataset
(http://www.gdal.org/gdal_vrttut.html) with 2 or more DEMs outside of
qgis/grass and r.external (Link GDAL supported raster file to a binary
raster map layer: http://grass.osgeo.org/grass64/manuals/r.external.html) or
r.in.gdal (Import GDAL supported raster file into a binary raster map layer:
http://grass.osgeo.org/grass64/manuals/r.in.gdal.html) the virtual raster.

HTH

best regards
Helmut

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4

The DEMs are over different areas beside each other, but within the mapset

and location,

ok, like this?

-------------------
| | |
|raster |raster |
| A | B |
-------------------

But when I load into NVIZ I can only chose one layer, DEMs in the mapset

listed....

you can only load raster A or raster B.

but try r.patch to combine both A+B to raster C and load
this raster in NVIZ ... or try the virtual gdal raster data set, it this the
same like r.patch, but only
virtual ...

-----
best regards
Helmut
--
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5

you can only load raster A or raster B.

oh, it's false, you can

nviz elevation=et-000-000@user1,et-000-001@user1

-----
best regards
Helmut
--
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