Hi,
After doing some more investigating, it appears g.proj is not reading all the parameters in :
proj=omerc +ellps=WGS84 +k_0=1.0 +lat_0=53.25 +no_uoff +rot_conv +alpha=-88 +lonc=-5.7
For example, the above command projects (-5.7d, 53.25d) correctly to (X,Y)=(-5901478, 7901021). But after g.proj, the same point projects to (X,Y)=(0,0).
Can someone help with this?
Thanks,
Garret
Dr. Garret Duffy
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Department of Earth and Ocean Sciences
National University of Ireland, Galway
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From: Duffy, Garret
Sent: 12-Oct-11 12:29 PM
To: ‘grass-user@lists.osgeo.org’
Subject: reprojection issue, using grass6.2
Hi,
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:
-PROJ_INFO-------------------------------------------------
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
-PROJ_UNITS------------------------------------------------
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 this.
Regards,
Garret