> >
> We have rasterdata in lat-lon which cover a large part of Europe (From Scandinavia to South-Europe; from the UK to east Russia). We need these data in a mapset with lcc coordinates.
> I rectified the maps with i.rectify2 (3rd order). I edited the POINTS-file for which I calculated the lcc coordinates for 15 points,distributed evenly over the area, exactly with m.proj.
> The results are, however too inaccurate (Especially in the corners: the British isles, the Greek islands and southern Italy). Now my question:
> Has anyone got a solution to increase the accuracy?
> It is a pitty that r.in.ll is not made for the other projections, but only for UTM.
I would use proj. It is relatively simple to convert a GRASS raster into the
format used by proj, then feed it back through s.to.rast:
r.stats -1g $1 | invproj +proj=utm +zone=$2 \
| proj +proj=aea +lon_0=96w +lat_0=23n | perl -ne 'print if /^[^*]/' \
| perl -ne 's/\s+/|/;s/\s+/|#/;print;' > \
$HOME/luda/location/greg/site_lists/${1:r}
In this example, I am converting utm rasters to the Albers projection. invproj
converts the utm coords to ll, then proj goes from ll to a U.S. Albers
projection (that is the default . . . you can override with arguments). The
two perl calls clean the result and reformat it as a GRASS sites file.
Try it, you'll like it!
greg
******************************************************************************
Greg Koerper Internet: greg@heart.cor.epa.gov
ManTech Environmental Technology, Inc.
US EPA Environmental Research Lab voice: (503) 754-4490
200 SW 35th St., JSB fax: (503) 754-4338
Corvallis, OR 97333
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