Re: [GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
On 03/07/08 15:39, Hamish wrote: You will lose information if you use r.composite, Just for my understanding: if you set levels to 256, you won't lose information, or ? It will just make displaying the result very slow. Moritz ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
Moritz Lennert wrote: You will lose information if you use r.composite, Just for my understanding: if you set levels to 256, you won't lose information, or ? It will just make displaying the result very slow. Correct. That assumes that the bands are limited to 256 levels. If you have more than that, it is impossible to generate a composite image without losing precision, as r.composite doesn't allow more than 256 levels. There isn't really much point; the only reason for generating a composite image is for display. For analysis, you are better off using separate bands. -- Glynn Clements [EMAIL PROTECTED] ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
Dear all, I intend to mosaic two 24 bit images in LAT LON location. I imported a 24 bit coloured PNG image in Grass using r.in.gdal in an x-y location. GRASS treated it as a combination of three 8 bit images, one for red, one for green, and one for blue and imported them as three separate maps. After going through the archives, I tried to use r.patch to combine all the three components. The output of which wasn't a 24bit image but was only one of the components. (Not coloured) d.rgb module does display a coloured 24 bit image after inputing the three components to it. I geocoded them to get non-coloured 8 bit geocoded images in the target location. I did the same for the second 24 bit image. Mosaicing works fine(i.image.mosaic), but i need to use 8 bit images(24 bit images converted to 8 bit images prior to importing, using xv; resolution weak) or any one of the 8 bit components of a 24 bit image. Is there a way to mosaic 24 bit images and to output it as a single 24 bit image? Regards Nagesh www.nio.org www.indian-ocean.org www.reefindia.org www.coastalhazards.info www.coastalhazards.in www.mangroveindia.org ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
On 03/07/08 14:35, Nagesh Bhatkar wrote: Dear all, I intend to mosaic two 24 bit images in LAT LON location. I imported a 24 bit coloured PNG image in Grass using r.in.gdal in an x-y location. GRASS treated it as a combination of three 8 bit images, one for red, one for green, and one for blue and imported them as three separate maps. After going through the archives, I tried to use r.patch to combine all the three components. The output of which wasn't a 24bit image but was only one of the components. (Not coloured) d.rgb module does display a coloured 24 bit image after inputing the three components to it. I geocoded them to get non-coloured 8 bit geocoded images in the target location. I did the same for the second 24 bit image. Mosaicing works fine(i.image.mosaic), but i need to use 8 bit images(24 bit images converted to 8 bit images prior to importing, using xv; resolution weak) or any one of the 8 bit components of a 24 bit image. Is there a way to mosaic 24 bit images and to output it as a single 24 bit image? r.composite (Raster-Manage map colors-Create RGB) Moritz ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
Hamish pisze: Nagesh wrote: Is there a way to mosaic 24 bit images and to output it as a single 24 bit image? To export a 24 bit image make a group of the 3 bands (i.group) and export the *group* using r.out.gdal (gdal_translate can do that also from outside GRASS, if you choose it's input as a path to your group file). This way you don't loose data as it would be the case for r.composite. Note that you can nicely visualise GRASS raster groups in QGIS, if at adding the GRASS raster layer you choose a group. Maciek -- Maciej Sieczka www.sieczka.org ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Is mosaicing 24 bit images possible in Grass 6.2?
On Thursday 03 July 2008, Maciej Sieczka wrote: Hamish pisze: Nagesh wrote: Is there a way to mosaic 24 bit images and to output it as a single 24 bit image? To export a 24 bit image make a group of the 3 bands (i.group) and export the *group* using r.out.gdal (gdal_translate can do that also from outside GRASS, if you choose it's input as a path to your group file). This way you don't loose data as it would be the case for r.composite. Note that you can nicely visualise GRASS raster groups in QGIS, if at adding the GRASS raster layer you choose a group. Maciek This is an excellent tip. Is this documented anywhere? Cheers, Dylan -- Dylan Beaudette Soil Resource Laboratory http://casoilresource.lawr.ucdavis.edu/ University of California at Davis 530.754.7341 ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
