On 15/06/2010 16:45, Dr. Manfred Redslob wrote:
Am Dienstag, den 15.06.2010, 06:39 -0700 schrieb varunvarma:
Hi, I am a new user to GRASS and have run into a problem while processing
rasters
I have 2 raster files (TIFFs) which I have loaded with GRASS in QGIS 1.0.2
Kore. The rasters contain values of 0 and 1 and represent 2 time steps. What
I wanted to do is either a simple addition of the 2 rasters or apply an OR
operator between them. For this I used the r.mapcalc and r.mapcalculator
tool. However, the cell size of the resulting raster is increased from 250m
to 2500m which leads to loss of fine scale information.
Does anyone know why this is happening and what I could do to maintain the
fine scale information?
Thank you
Hi however,
please check the actual resolution with g.region -p. Is the result
res=2500? If so, set region with g.region -ap res=250 or with g.region
rast=inputrasterfile. You can controll it again with g.region -p. After
this settings run r.mapcalc again.
Regards,
Manfred
In addition, to do the same thing within QGIS, you can use the "Edit
current region" button on the GRASS toolbar. Just enter the value you
need in the N-S resolution and E-W text boxes.
Another note: I might suggest you upgrade to a newer version of QGIS.
Version 1.4 (and soon to be released 1.5) have many improvements and bug
fixes.
Regards
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--
Micha Silver
http://www.surfaces.co.il/
Arava Development Co. +972-52-3665918
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