[Proj] forward/inverse projection logic for ob_tran
Hermann Peifer
peifer at gmx.eu
Sun Oct 9 09:06:41 EST 2011
Hi,
I am currently dealing with regional climate models, where the data
comes in form of "rotated pole lat/lon grids", with the North Pole at
39.25N, 162W.
I am able to convert "rotated pole coordinates" to "normal lat/lon
coordinates" by using:
$ proj -f "%.6f" -m 57.2957795130823 +proj=ob_tran +o_proj=latlon
+o_lon_p=-162 +o_lat_p=39.25 +lon_0=180
It looks to me that the proj/invproj (i.e. forward/inverse) projection
logic is opposite to what I would expect: I need to run proj (i.e. the
forward projection) in order get from the "rotated lat/lon" coordinates
(say: lon=0,lat=0) back to the "normal lat/lon coordinates" (here:
lon=18.0,lat=50.75), and vice versa.
Is this expected behaviour? If yes: what am I missing?
Thanks for your time, Hermann
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