RE: [GRASS-user] Using g.setproj to "fix" PROJ_INFO

Well, I would rather fix the problem of incorrect Location projection
parameters if that is the problem - may as well fix the problem at the
source if possible.

~ Eric.

-----Original Message-----
From: Maciek Sieczka
To: Patton, Eric
Cc: grassuser@grass.itc.it
Sent: 5/14/2006 8:42 AM
Subject: Re: [GRASS-user] Using g.setproj to "fix" PROJ_INFO

On Fri, 12 May 2006 13:46:26 -0300
"Patton, Eric" <epatton@nrcan.gc.ca> wrote:

Hey guys,

A colleague is having problems with an archaic Grass project in that
geotiffs created from rasters in this Location only display correctly
in ArcGIS in UTM Zone 20 despite g.proj -p saying that the Location
is UTM Zone 19.

What do the gdalinfo say about your geotiffs?

All the projection info I can find on data in this
Location says it's UTM 19, but the data displays as UTM20. We're
pretty sure that the ArcGIS data used as a check against the Grass
data is correct (let's assume so for the sake of this argument). Is
it ok to go ahead and make backups of PROJ_INFO and PROJ_UNITS,
delete the originals, and then run g.setproj to make new info files?
Are there any dangers to doing this? This is uncharted waters for me.

You could use gdal_translate -a_srs to correct the projection in the
output file.

Maciek

--------------------
W polskim Internecie s? setki milion?w stron. My przekazujemy Tobie
tylko najlepsze z nich!
http://katalog.panoramainternetu.pl/

You can manually edit the PROJ_INFO, WIND and DEFAULT_WIND files just to change the zone number. That should be all you need---but you might come across problems with raster maps in the location that have the zone number embedded in their header files; I'm not sure. Re-running g.setproj will do no harm either and might be a good idea if the location is very old.

Paul

On Mon, 15 May 2006, Patton, Eric wrote:

Well, I would rather fix the problem of incorrect Location projection
parameters if that is the problem - may as well fix the problem at the
source if possible.

~ Eric.

-----Original Message-----
From: Maciek Sieczka
To: Patton, Eric
Cc: grassuser@grass.itc.it
Sent: 5/14/2006 8:42 AM
Subject: Re: [GRASS-user] Using g.setproj to "fix" PROJ_INFO

On Fri, 12 May 2006 13:46:26 -0300
"Patton, Eric" <epatton@nrcan.gc.ca> wrote:

Hey guys,

A colleague is having problems with an archaic Grass project in that
geotiffs created from rasters in this Location only display correctly
in ArcGIS in UTM Zone 20 despite g.proj -p saying that the Location
is UTM Zone 19.

What do the gdalinfo say about your geotiffs?

All the projection info I can find on data in this
Location says it's UTM 19, but the data displays as UTM20. We're
pretty sure that the ArcGIS data used as a check against the Grass
data is correct (let's assume so for the sake of this argument). Is
it ok to go ahead and make backups of PROJ_INFO and PROJ_UNITS,
delete the originals, and then run g.setproj to make new info files?
Are there any dangers to doing this? This is uncharted waters for me.

You could use gdal_translate -a_srs to correct the projection in the
output file.

Maciek

--------------------
W polskim Internecie s? setki milion?w stron. My przekazujemy Tobie
tylko najlepsze z nich!
http://katalog.panoramainternetu.pl/

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