[GRASS-user] How to generate map subsets?

GRASS GRASS user
1

Hi all

I am new to GRASS (but not GIS), and am sitting with the latest edition of the “Open Source GIS” book in the evenings. I have a simple problem with subsetting a large raster file.

I have SRTM data for a large area (1.9GB), and need to extract a subset of the data. I save a region (“ecoast”) for the area I want to extract, load it and then use r.mapcalc to create a subarea but there is an error and no output raster is created.

I am typing the commands in a GRASS shell called from the GRASS tools menu, and attach my steps following p91 of the book. Any suggestions appreciated!

Thanks
Brendon Wolff-Piggott

user@USER-5F22862413 /c/documents and settings/user/grassdata/rsa/geographic
$ g.region “region=ecoast”

user@USER-5F22862413 /c/documents and settings/user/grassdata/rsa/geographic
$ r.mapcalc “srtm_ecoast=srtm_rsa”

GRASS_INFO_ERROR(804,1): Unable to close raster map
GRASS_INFO_END(804,1)

2

On Thu, Oct 9, 2008 at 12:01 PM, brendon wolff-piggott
<mytekmail@gmail.com> wrote:

Hi all

I am new to GRASS (but not GIS), and am sitting with the latest edition of
the "Open Source GIS" book in the evenings. I have a simple problem with
subsetting a large raster file.

I have SRTM data for a large area (1.9GB), and need to extract a subset of
the data. I save a region ("ecoast") for the area I want to extract, load
it and then use r.mapcalc to create a subarea but there is an error and no
output raster is created.

I am typing the commands in a GRASS shell called from the GRASS tools menu,
and attach my steps following p91 of the book. Any suggestions appreciated!

Thanks
Brendon Wolff-Piggott

user@USER-5F22862413 /c/documents and settings/user/grassdata/rsa/geographic
$ g.region "region=ecoast"

Please post

g.region region=ecoast -p

to understand at which resolution you create the new map (if not the
original res.).

user@USER-5F22862413 /c/documents and settings/user/grassdata/rsa/geographic
$ r.mapcalc "srtm_ecoast=srtm_rsa"

GRASS_INFO_ERROR(804,1): Unable to close raster map
GRASS_INFO_END(804,1)

possilby you have nanometer resolution and try to generate a XXGB file?
Disk full?

Markus