Le Sun, 28 May 2017 08:29:48 -0400, Ken Mankoff <mank...@gmail.com> a écrit :
> Hi List, > > I'm trying to set up a polar projection and draw some grid lines. I'm > having trouble a) getting the grid lines to the pole and b) rotating > it so a different longitude is the center longitude. I'm using the > following code: > > grass72 -e -c epsg:3413 ./tmp > grass72 ./tmp/PERMANENT > > xy0=$(m.proj -i coordinates=0,40) # set corners to 40° N > xy1=$(m.proj -i coordinates=180,40) > x0=$(echo ${xy0} | cut -d"|" -f1) > y0=$(echo ${xy0} | cut -d"|" -f2) > x1=$(echo ${xy1} | cut -d"|" -f1) > y1=$(echo ${xy1} | cut -d"|" -f2) > > g.region s=${y0} n=${y1} w=${x1} e=${x0} > > d.mon start=wx0 > d.erase > d.grid -w size=10:0 > > > The d.grid manual suggests calling 2x near the poles, but even doing > that (e.g. d.grid -w size=1 direction=east-west) does not improve > where the grid lines are drawn. Also, if I wanted Russia, not > Greenland, pointing "down" on the map, how do I rotate this > projection? > Can't help you with you grid problems right now, but for "rotating" your projection, you would have to create a new location with modified projection parameters. Just change the lon_0 value to whatever meridian you want as central: Original EPSG 3413 : +proj=stere +lat_0=90 +lat_ts=70 +lon_0=-45 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs <> Centered on Novosibirsk: +proj=stere +lat_0=90 +lat_ts=70 +lon_0=83 +k=1 +x_0=0 +y_0=0 +datum=WGS84 +units=m +no_defs <> You can then create the new location using the "custom PROJ.4 parameters" option for defining the projection and pasting the above definition. Moritz _______________________________________________ grass-user mailing list grass-user@lists.osgeo.org https://lists.osgeo.org/mailman/listinfo/grass-user