I have been having no luck today working with DEMs in GRASS. I have tried several sources for DEM data derived from 24k quads. I can bring in the dem and it will draw with color as expected. If I query the map, I do not get elevation:
449208.962656|4171350.10373||*
If I try to produce a hillshade from the map, it is blank. This is making me a bit insane because I have done these things before without issue. I have no problem using the dem in the spearfish dataset.
I am unable to get things working using a 24k dem from:
ftp://nas.library.unr.edu/keck/30mDEM/30mdemzip/quad1113.zip
After renaming the .dem file to alcatraz_island (although I also tried using a NED file in another format with no name changes), I ran:
r.in.gdal input=alcatraz_island.dem output=alcatraz_island_dem
The colors are there in my region and can be changed with r.colors as expected, but I still have nothing returned on query. I am trying to use r.mapcalc or r.recode to derive a band along a contour, but I only get empty files returned. Is there something simple I am overlooking.
This happens with both 6.2.2 and 6.3cvs.
Thanks,
John Tull
John,
did you run
g.region rast=demmap -p
first? You have to set the current region to the map (or spatial subset) to
work with it.
Markus
John C. Tull wrote on 07/24/2007 07:19 AM:
I have been having no luck today working with DEMs in GRASS. I have
tried several sources for DEM data derived from 24k quads. I can bring
in the dem and it will draw with color as expected. If I query the
map, I do not get elevation:
449208.962656|4171350.10373||*
If I try to produce a hillshade from the map, it is blank. This is
making me a bit insane because I have done these things before without
issue. I have no problem using the dem in the spearfish dataset.
I am unable to get things working using a 24k dem from:
ftp://nas.library.unr.edu/keck/30mDEM/30mdemzip/quad1113.zip
After renaming the .dem file to alcatraz_island (although I also tried
using a NED file in another format with no name changes), I ran:
r.in.gdal input=alcatraz_island.dem output=alcatraz_island_dem
The colors are there in my region and can be changed with r.colors as
expected, but I still have nothing returned on query. I am trying to
use r.mapcalc or r.recode to derive a band along a contour, but I only
get empty files returned. Is there something simple I am overlooking.
This happens with both 6.2.2 and 6.3cvs.
Thanks,
John Tull
------------------
ITC -> dall'1 marzo 2007 Fondazione Bruno Kessler
ITC -> since 1 March 2007 Fondazione Bruno Kessler
------------------
Markus,
Thanks for that advice. The problem is solved. So, for the record, if you are working with a region that is larger than the raster, but includes the raster, will the problems I was having occur?
Cheers,
John
On Jul 24, 2007, at 1:32 AM, Markus Neteler wrote:
John,
did you run
g.region rast=demmap -p
first? You have to set the current region to the map (or spatial subset) to
work with it.
Markus
John C. Tull wrote on 07/24/2007 07:19 AM:
I have been having no luck today working with DEMs in GRASS. I have
tried several sources for DEM data derived from 24k quads. I can bring
in the dem and it will draw with color as expected. If I query the
map, I do not get elevation:
449208.962656|4171350.10373||*
If I try to produce a hillshade from the map, it is blank. This is
making me a bit insane because I have done these things before without
issue. I have no problem using the dem in the spearfish dataset.
I am unable to get things working using a 24k dem from:
ftp://nas.library.unr.edu/keck/30mDEM/30mdemzip/quad1113.zip
After renaming the .dem file to alcatraz_island (although I also tried
using a NED file in another format with no name changes), I ran:
r.in.gdal input=alcatraz_island.dem output=alcatraz_island_dem
The colors are there in my region and can be changed with r.colors as
expected, but I still have nothing returned on query. I am trying to
use r.mapcalc or r.recode to derive a band along a contour, but I only
get empty files returned. Is there something simple I am overlooking.
This happens with both 6.2.2 and 6.3cvs.
Thanks,
John Tull
------------------
ITC -> dall'1 marzo 2007 Fondazione Bruno Kessler
ITC -> since 1 March 2007 Fondazione Bruno Kessler
------------------
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