Re: [GRASS-user] Extract a smaller image (sample) from a raster map
Many thanks for the step by step explanation and side note!! That was of great help to me : -) Now is working! I deleted locations and created a new one making sure I wasn´t missing anything. Have just used *G.region* and follow the step outlined here. - Lbxa -- View this message in context: http://osgeo-org.1560.x6.nabble.com/Extract-a-smaller-image-sample-from-a-raster-map-tp5063094p5064450.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
[GRASS-user] Extract a smaller image (sample) from a raster map
Many thanks for the explanation! I read the links you have posted and others like specific to r.region and g.region, still a bit confuse with some concepts. HOWEVER, still not able yet to extract a smaller image from the bigger one!. Have used *g.region* setting the values of a smaller area, and have set it as computational region but the image displayed is the same. I did the same importing a new image and setting r.region but not getting any difference! Feel a little bit frustrated -- View this message in context: http://osgeo-org.1560.x6.nabble.com/Extract-a-smaller-image-sample-from-a-raster-map-tp5063094p5063102.html Sent from the Grass - Users mailing list archive at Nabble.com. ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Extract a smaller image (sample) from a raster map
Lbxa wrote: Many thanks for the explanation! (Thanks to the guys spending nights to code all that stuff...) I read the links you have posted and others like specific to r.region and g.region, still a bit confuse with some concepts. HOWEVER, still not able yet to extract a smaller image from the bigger one!. Have used *g.region* setting the values of a smaller area, and have set it as computational region but the image displayed is the same. I did the same importing a new image and setting r.region but not getting any difference! Feel a little bit frustrated (No pain, no Gain :-p). So, one step at a time, and assuming you have created a Location based on the Spatial Reference System in which your data are defined/projected: 1. import raster map(s) using r.in.gdal -- nothing else required (no r.region required unless something is wrong with the imported data) 2. set the computational region using g.region, e.g. - g.region rast=YourRastMap will set the computational region to match the extent of your raster map (which is _not_ what you are after, if I got it right) - g.region w= e= s= n= to set a custom defined computational region 3. r.mapcalc Test = YourRasterMap -- this will simply copy YourRasterMap, yet, only for inside the computational region! Hope this helps a bit, Nikos ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Extract a smaller image (sample) from a raster map
Nikos wrote: 2. set the computational region using g.region, e.g. - g.region rast=YourRastMap will set the computational region to match the extent of your raster map (which is _not_ what you are after, if I got it right) - g.region w= e= s= n= to set a custom defined computational region just a little side note, at this point in the process it is always good to check the computational region result with 'g.region -p', if the bounds and or resolution got messy you can fix it with the 'g.region align=original_map' command, or 'g.region -a res=...' at the chosen resolution. also, if you changed anything with r.region it is probably best to delete the first attempt and re-import the map from the raw file. Hamish ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
