Dear all,
I am new to both Grass and this forum, so apologies in advance for something
which is likely a simple mistake or oversight on my part (but I have
searched the forum and can't seem to find an answer).
I am trying to create RGB-composite images from various sets of Landsat
bands (3,2,1 or 4,5,3). When I try to do this using r.composite, the
resulting raster file has a far courser pixel resolution than the original
images (it looks like it is scaling up by a factor of 12 - so 30m x 30m
pixels become 360m x 360m). I can't see anything in the r.composite manual
that suggests why this would be happening.
If it is relevant, I am also using i.landsat.rgb to balance the colours
before I am using the r.composite. Also, I am using Grass 6.3, and running
it through the plugin on QGIS 0.11.0.
Thanks in advance for any help.
Tim
--
View this message in context: http://n2.nabble.com/r.composite-changing-pixel-resolution--tp2320123p2320123.html
Sent from the Grass - Users mailing list archive at Nabble.com.
Hi Tim and all!
2009/2/13 Tim Holland <timothyholland@gmail.com>:
Dear all,
I am new to both Grass and this forum, so apologies in advance for something
which is likely a simple mistake or oversight on my part (but I have
searched the forum and can't seem to find an answer).
I am trying to create RGB-composite images from various sets of Landsat
bands (3,2,1 or 4,5,3). When I try to do this using r.composite, the
resulting raster file has a far courser pixel resolution than the original
images (it looks like it is scaling up by a factor of 12 - so 30m x 30m
pixels become 360m x 360m). I can't see anything in the r.composite manual
that suggests why this would be happening.
If it is relevant, I am also using i.landsat.rgb to balance the colours
before I am using the r.composite. Also, I am using Grass 6.3, and running
it through the plugin on QGIS 0.11.0.
When you run a command that produces a new map, usually the new map
has the size and resolution of the active region, not far and the
resolution of input maps.
To check the values of the active region, use the following command:
g.region-p
To set the values of the active region to the same values as their
input maps, use:
RAST g.region P = name_of_raster_map
To check the values of some map, use:
r.info map name_of_raster_map =
I hope this helps!
Saludos
José María
Ops! Sorry, I used the translator incorrectly!
Corrections:
To check the values of the active region, use the following command:
g.region -p
To set the values of the active region to the same values as their
input maps, use:
g.region -p rast=name_of_raster_map
To check the values of some map, use:
r.info map=name_of_raster_map
And an important note: I'm not sure if this information is applicable
using the plugin in QGIS.
Please, sorry again, I make many mistake but with the best intentions!
Saludos
2009/2/13 José María Michia <jose.maria.michia@gmail.com>:
Hi Tim and all!
2009/2/13 Tim Holland <timothyholland@gmail.com>:
Dear all,
I am new to both Grass and this forum, so apologies in advance for something
which is likely a simple mistake or oversight on my part (but I have
searched the forum and can't seem to find an answer).
I am trying to create RGB-composite images from various sets of Landsat
bands (3,2,1 or 4,5,3). When I try to do this using r.composite, the
resulting raster file has a far courser pixel resolution than the original
images (it looks like it is scaling up by a factor of 12 - so 30m x 30m
pixels become 360m x 360m). I can't see anything in the r.composite manual
that suggests why this would be happening.
If it is relevant, I am also using i.landsat.rgb to balance the colours
before I am using the r.composite. Also, I am using Grass 6.3, and running
it through the plugin on QGIS 0.11.0.
When you run a command that produces a new map, usually the new map
has the size and resolution of the active region, not far and the
resolution of input maps.
To check the values of the active region, use the following command:
g.region-p
To set the values of the active region to the same values as their
input maps, use:
RAST g.region P = name_of_raster_map
To check the values of some map, use:
r.info map name_of_raster_map =
I hope this helps!
Saludos
José María
Dear Jose Maria -
Thanks very much! That did it.
Best,
Tim
On Fri, Feb 13, 2009 at 3:54 PM, José María Michia
<jose.maria.michia@gmail.com> wrote:
Ops! Sorry, I used the translator incorrectly!
Corrections:
To check the values of the active region, use the following command:
g.region -p
To set the values of the active region to the same values as their
input maps, use:
g.region -p rast=name_of_raster_map
To check the values of some map, use:
r.info map=name_of_raster_map
And an important note: I'm not sure if this information is applicable
using the plugin in QGIS.
Please, sorry again, I make many mistake but with the best intentions!
Saludos
2009/2/13 José María Michia <jose.maria.michia@gmail.com>:
Hi Tim and all!
2009/2/13 Tim Holland <timothyholland@gmail.com>:
Dear all,
I am new to both Grass and this forum, so apologies in advance for something
which is likely a simple mistake or oversight on my part (but I have
searched the forum and can't seem to find an answer).
I am trying to create RGB-composite images from various sets of Landsat
bands (3,2,1 or 4,5,3). When I try to do this using r.composite, the
resulting raster file has a far courser pixel resolution than the original
images (it looks like it is scaling up by a factor of 12 - so 30m x 30m
pixels become 360m x 360m). I can't see anything in the r.composite manual
that suggests why this would be happening.
If it is relevant, I am also using i.landsat.rgb to balance the colours
before I am using the r.composite. Also, I am using Grass 6.3, and running
it through the plugin on QGIS 0.11.0.
When you run a command that produces a new map, usually the new map
has the size and resolution of the active region, not far and the
resolution of input maps.
To check the values of the active region, use the following command:
g.region-p
To set the values of the active region to the same values as their
input maps, use:
RAST g.region P = name_of_raster_map
To check the values of some map, use:
r.info map name_of_raster_map =
I hope this helps!
Saludos
José María