For some reason, the moderator isn't approving this message, but I'll post it again assuming a computer glitch.
Yes, I know it is frustrating to deal with newbies, but we all have to start somewhere.
My ultimate goal for GRASS is to do viewshed analysis with r.los. I have downloaded NED files from the USGS seamless website. I have also managed to convert the .adf file to geotiff using gdal_translate.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I get an error message regarding the default region is not set. I gather I'm not initializing GRASS properly.
I'm using my own PC, so I can run as root to avoid directory permission issues.
I have the "Grass 6 in a nutshell handy" if you need to reference it.
If you don't need to match this DEM up with any existing grass data
(ie you want to create a fresh new location), you can use the
location= parameter on the r.in.gdal command to create the location
automatically based on the info contained in the DEM. Then exit out of
grass and start it back up and you should see your new location in the
list. Likewise your DEM should be imported into that location and you
can start playing with some GRASS tools.
Hope this helps a bit.
- matt
On 6/8/06, gary <lists@lazygranch.com> wrote:
For some reason, the moderator isn't approving this message, but I'll
post it again assuming a computer glitch.
Yes, I know it is frustrating to deal with newbies, but we all have to
start somewhere.
My ultimate goal for GRASS is to do viewshed analysis with r.los. I have
downloaded NED files from the USGS seamless website. I have also managed
to convert the .adf file to geotiff using gdal_translate.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
I'm using my own PC, so I can run as root to avoid directory permission
issues.
I have the "Grass 6 in a nutshell handy" if you need to reference it.
On Thu, 08 Jun 2006 18:49:42 -0700
gary <lists@lazygranch.com> wrote:
For some reason, the moderator isn't approving this message, but I'll
post it again assuming a computer glitch.
Yes, I know it is frustrating to deal with newbies, but we all have to
start somewhere.
No problem.
My ultimate goal for GRASS is to do viewshed analysis with r.los. I have
downloaded NED files from the USGS seamless website. I have also managed
to convert the .adf file to geotiff using gdal_translate.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
I'm using my own PC, so I can run as root to avoid directory permission
issues.
This shouldn't be necessary except for your install of GRASS.
I have the "Grass 6 in a nutshell handy" if you need to reference it.
Lets cover the basics. I assume that you know the projection of the
image you want to use. Further, you've created a location which has
the same projection parameters? Now if you don't have anything in that
location yet and you are having problems, I would just delete it from
an xterm and start over. In the Grass 6 in a nutshell there is a
section on creating locations. I would review it and try again. If it
is still odd I would then use g.region -p and g.proj -p and see what
you get and how that matches or doesn't match with your file.
When you are setting up a region, you don't need to worry about extents
as their is an option in r.in.gdal to expand the extents of the current
region to match the source image.
HTH.
T
--
Trevor Wiens
twiens@interbaun.com
The significant problems that we face cannot be solved at the same
level of thinking we were at when we created them.
(Albert Einstein)
My ultimate goal for GRASS is to do viewshed analysis with r.los. I
have downloaded NED files from the USGS seamless website. I have also
managed to convert the .adf file to geotiff using gdal_translate.
Can't you download NED data directly as GeoTIFF?
Some hints:
r.los doesn't scale well at all. Download "r.cva" (install with GRASS GEM?)
and use that instead if you can.
Also see hints on r.sun and r.sunmask page.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
The new GRASS 6.1 startup has an option to create a location from a
georeferenced map.
If you already have a location (i.e., projection) set up and something in
it, but are having region issues, you can use g.region to set the region of
interest to match the map you have
G.region rast=[mapname]
This will set up the region properly to match the resolution and extents of
your map.
I should also point out that NED are derived from topo contour lines and
often have poorly interpolated topography, such that they have a step-like
quality. I'd recommend using the 30m SRTM's instead. I haven't had trouble
with r.los, but r.cva is a much more versatile tool. It's only drawback is
it's EXTREME slowness when doing multiple viewsheds.
Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
From: Hamish <hamish_nospam@yahoo.com>
Date: Fri, 9 Jun 2006 21:24:47 +1200
To: gary <lists@lazygranch.com>
Cc: <grassuser@grass.itc.it>
Subject: Re: [GRASS-user] Newbie question on g.region
My ultimate goal for GRASS is to do viewshed analysis with r.los. I
have downloaded NED files from the USGS seamless website. I have also
managed to convert the .adf file to geotiff using gdal_translate.
Can't you download NED data directly as GeoTIFF?
Some hints:
r.los doesn't scale well at all. Download "r.cva" (install with GRASS GEM?)
and use that instead if you can.
Also see hints on r.sun and r.sunmask page.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
The link above indicates the 30m SRTMs are 1 arcsecond resolution. While I am going to first use the 1 arcsecond NED, there are 1/3 arcsecond NEDs available. Would the 30m SRTMs be superior to a 1/3 arcsecond NED?
Michael Barton wrote:
The new GRASS 6.1 startup has an option to create a location from a
georeferenced map.
If you already have a location (i.e., projection) set up and something in
it, but are having region issues, you can use g.region to set the region of
interest to match the map you have
G.region rast=[mapname]
This will set up the region properly to match the resolution and extents of
your map.
I should also point out that NED are derived from topo contour lines and
often have poorly interpolated topography, such that they have a step-like
quality. I'd recommend using the 30m SRTM's instead. I haven't had trouble
with r.los, but r.cva is a much more versatile tool. It's only drawback is
it's EXTREME slowness when doing multiple viewsheds.
Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
From: Hamish <hamish_nospam@yahoo.com>
Date: Fri, 9 Jun 2006 21:24:47 +1200
To: gary <lists@lazygranch.com>
Cc: <grassuser@grass.itc.it>
Subject: Re: [GRASS-user] Newbie question on g.region
My ultimate goal for GRASS is to do viewshed analysis with r.los. I
have downloaded NED files from the USGS seamless website. I have also
managed to convert the .adf file to geotiff using gdal_translate.
Can't you download NED data directly as GeoTIFF?
Some hints:
r.los doesn't scale well at all. Download "r.cva" (install with GRASS GEM?)
and use that instead if you can.
Also see hints on r.sun and r.sunmask page.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
I don't know. In a remote sensing class I just co-taught with a
geomorphologist colleague, we did some comparisons between the NED and SRTM
data. The SRTM data were better at 30m at least.
Do a slope map (r.slope.aspect) of the NED data and see if it is striped,
indicating the contour line stepping.
Also subtract it from an SRTM to see if there is systematic error derived
from poor interpolation.
Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics and Complexity
Arizona State University
From: gary <lists@lazygranch.com>
Date: Fri, 09 Jun 2006 09:55:53 -0700
To: Michael Barton <michael.barton@asu.edu>
Cc: <grassuser@grass.itc.it>
Subject: Re: [GRASS-user] Newbie question on g.region
The link above indicates the 30m SRTMs are 1 arcsecond resolution. While
I am going to first use the 1 arcsecond NED, there are 1/3 arcsecond
NEDs available. Would the 30m SRTMs be superior to a 1/3 arcsecond NED?
Michael Barton wrote:
The new GRASS 6.1 startup has an option to create a location from a
georeferenced map.
If you already have a location (i.e., projection) set up and something in
it, but are having region issues, you can use g.region to set the region of
interest to match the map you have
G.region rast=[mapname]
This will set up the region properly to match the resolution and extents of
your map.
I should also point out that NED are derived from topo contour lines and
often have poorly interpolated topography, such that they have a step-like
quality. I'd recommend using the 30m SRTM's instead. I haven't had trouble
with r.los, but r.cva is a much more versatile tool. It's only drawback is
it's EXTREME slowness when doing multiple viewsheds.
Michael
__________________________________________
Michael Barton, Professor of Anthropology
School of Human Evolution & Social Change
Center for Social Dynamics & Complexity
Arizona State University
From: Hamish <hamish_nospam@yahoo.com>
Date: Fri, 9 Jun 2006 21:24:47 +1200
To: gary <lists@lazygranch.com>
Cc: <grassuser@grass.itc.it>
Subject: Re: [GRASS-user] Newbie question on g.region
My ultimate goal for GRASS is to do viewshed analysis with r.los. I
have downloaded NED files from the USGS seamless website. I have also
managed to convert the .adf file to geotiff using gdal_translate.
Can't you download NED data directly as GeoTIFF?
Some hints:
r.los doesn't scale well at all. Download "r.cva" (install with GRASS GEM?)
and use that instead if you can.
Also see hints on r.sun and r.sunmask page.
My problem concerns starting up GRASS. When I try to run r.in.gdal, I
get an error message regarding the default region is not set. I gather
I'm not initializing GRASS properly.
When running r.los, I am getting the error message "lat/long databases not yet supported".
The X,y coordinates were printed back correctly in the error message. I entered them in the format Ndd hh mm.m Wdd hh mm.m. I made sure the location is in the raster map.
I'm running Grass60. BTW, I did look into the suggestion of using r.cva, but it doesn't seem to be supported in Grass 6.
When running r.los, I am getting the error message "lat/long databases not yet supported".
The X,y coordinates were printed back correctly in the error message. I entered them in the format Ndd hh mm.m Wdd hh mm.m. I made sure the location is in the raster map.
I'm running Grass60. BTW, I did look into the suggestion of using r.cva, but it doesn't seem to be supported in Grass 6.
gary wrote:
> When running r.los, I am getting the error message "lat/long
> databases not yet supported".
>
> The X,y coordinates were printed back correctly in the error
> message. I entered them in the format Ndd hh mm.m Wdd hh mm.m. I
> made sure the location is in the raster map.
>
> I'm running Grass60. BTW, I did look into the suggestion of using
> r.cva, but it doesn't seem to be supported in Grass 6.
..
Ignore the prior post. I found a tutorial explaining the error message
and will attempt to convert my data to UTM.