[GRASS-user] reprojection issue, using grass6.2

Duffy, Garret garret.duffy at nuigalway.ie
Wed Oct 12 07:29:04 EDT 2011


I have three locations defined, one in Geographic 'projection', one UTM
and the other described below.  When I try to reproject data, e.g. a
vector rectangle from either Geographic or UTM to the Oblique Mercator
projection defined below, the rectangle isn't rotated as I expect.  The
origin of the projected coordinates looks to be in the correct location
but there is no rotation applied (geographic north is supposed to ~45
deg from the y axis).  BTW, is it even possible to display a geodetic
grid for a non-rectified projection?

output from g.proj -p:
name       : Oblique Mercator
proj       : omerc
a          : 6378137
es         : 0.006694379990141316
lat_0      : 53.25
lonc       : -5.7
alpha      : -88
k          : 1
x_0        : 0
y_0        : 0
towgs84    : 0,0,0,0,0,0,0
no_defs    : defined
unit       : meter
units      : meters
meters     : 1

The command I used to specify the oblique projection is:

proj +proj=omerc +ellps=WGS84 +k_0=1.0 +lat_0=53.25 +no_uoff +rot_conv
+alpha=-88 +lonc=-5.7

I must emphasize that I have checked the proj.4 parameters using the
command-line proj.4 and the *parameters are correct*.  I applied these
parameters in GlobalMapper to get the final map to the state that I
would like eventually in GRASS.

Any advice would be *greatly* appreciated, I have spent a lot of time on


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