[GRASS-user] A resolution problem with r.patch + r.proj

[Silvia Simoni]

Hi,

I 'm trying to reproject a raster map from a location Gauss-Boaga to  
UTM-WGS84.
The map in Gauss Boaga was created using r.patch from 4 maps imported  
from a geotif file.

I describe the procedure below to be more precise:
from the GB location
- r.in.gdal on the 4 tif files (the tfw was 0.25, 0, 0, -0.25, East,  
North)
- g.region -p to check that the resolution of the imported map was 0.25
- g.region rast=map1, map2,map3,map4
- g.region -p  to check if the resolution was still 0.25m; I noticed  
it changed to nsres 0.2499987 and ewres 0.2499915
- r.patch map=map1, map2, map3, map4
from the UTM location
-r.proj .....  res=?

I read that the resolution should be kept the same when reprojecting.

1st question: can I force the resolution to remain 0.25m when  
launching r.patch?
2nd question: when launching r.proj I am asked only one value for the  
resolution, what should I write in my case?

thanks,

silvia
----------------------------------------------------------------------------------------
Silvia Simoni PhD
DICA - Department of Civil and Environmental Engineering
Universita' di Trento
via Mesiano 77, 38100 Trento, ITALY
tel. +39 0461 882610
fax. +39 0461 882672
e-mail: silvia.simoni at ing.unitn.it