Jana K. pisze:
I've already posted this a couple of days ago, but I am afraid
somehow it got lost in other questions. I believe someone must know
an answer, so please, HELP me :-(:
I need to transform a map from LAEA coordinates into UTM. I created a
new location with UTM projection. I used r.proj from within the new
location, but running it, I received the following error message:
Input Projection Parameters: +proj=laea +lat_0=52.0000000000
+lon_0=10.0000000000 +x_0=4321000.0000000000 +y_0=3210000.0000000000
+a=6378137 +rf=298.257222101 +no_defs +towgs84=0.000,0.000,0.000
Input Unit Factor: 1
Output Projection Parameters: +proj=utm +zone=34 +a=6378137
+rf=298.257223563 +no_defs +towgs84=0.000,0.000,0.000 Output Unit
Factor: 1
Can't work with xy data
I don't understand it as the data are clearly georeferenced.
Looks like you do have correct settings in the PROJ_INFO in both
PERMANENT mapsets. Can you post the header file of the raster map you
want to reproject? Maybe it's malformed, for whatever reason. You'll
find it in location/mapset/cellhd folder.
Do I need to make a transformation to lat/lon beforehand?
In general avoid reprojecting rasters more often than needed - each
reprojection introduces some distortion to data.
Now question 2:
My raster data are categorical (landuse), and during the projection
transformation I want to go from high resolution (100m) to rather
crude resolution (2500m). How GRASS handles such operation? I would
expect that It assigns the highest frequency value to the new cell (I
mean if one new cell contains 625 old pixels, it will be assigned the
value which occurs most frequently). Am I right?
Look into section 'Design of r.proj' in the r.proj manual. In 'NOTES'
you'll find instructions on how to maintain input and output region
settings.
Best,
Maciek
--
Maciej Sieczka
www.sieczka.org
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