On Tue, 20 Sep 2016, Helmut Kudrnovsky wrote:

If it is about raster reprojection, there are hints in the r.proj manual
about region settings before applying r.proj.

A simple way to do this is to check the projected bounds of the input map
in the current location's projection using the -p flag. The -g flag
reports the same thing, but in a form which can be directly cut and pasted
into a g.region command. After setting the region in that way you might
check the cell resolution with "g.region -p" then snap it to a regular
grid with g.region's -a flag. E.g. g.region -a res=5 -p. Note that this is
just a rough guide.

A more involved, but more accurate, way to do this is to generate a vector
"box" map of the region in the source location using v.in.region -d. This
"box" map is then reprojected into the target location with v.proj. Next
the region in the target location is set to the extent of the new vector
map with g.region along with the desired raster resolution (g.region -m
can be used in Latitude/Longitude locations to measure the geodetic length
of a pixel). r.proj is then run for the raster map the user wants to
reproject. In this case a little preparation goes a long way.


  Thank you very much. This expansion of Micha's explanation is really
valuable and I greatly appreciate it. I wasn't aware of this need and
process the last time (years ago) I had a need to reproject data. Source
data in recent projects were all in the same projection and appropriate to
the area studied.


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