Le 02/12/2010 20:14, Paul Kelly a écrit :
On Thu, 2 Dec 2010, Thibault Lemaitre wrote:
I updated the tutorial in question. There was some problem in the
previous version : the modification of the PROJ_INFO file was not
good and the grid file needs to be in the nad directory of GRASS. The
method explained by the tutorial, needs the administrator rights on
Linux.
Somebody knows more about the nadgrids specification in the PROJ_INFO
file ? I mean, how to set a grid which is not in the nad directory of
GRASS ? If there is this possibility, a simple normal user would be
able to that.
You should be able to just put the full path in the PROJ_INFO file -
does that not work? If not can you post the contents of the PROJ_INFO
file to the list.
I first try with "/usr/share/proj/ntf_r93.gsb".
I didn't try with something like "../../ntf_r93.gsb" (with the grid put
in the grassdata folder). Should I try it or it's useless and won't work?
We should probably include the French gridshift file for datum
transformations NTF <--> RGF93 in the GRASS distribution, like we do
for the USA, Canada, New Zealand files. That would make it very easy
to use. How large is the file?
Like I write on the tutorial
<http://grass.osgeo.org/wiki/IGNF_register_and_shift_grid_NTF-RGF93>,
the grid can be found on the IGN Lambert 93 website. It weight 271 Kio
(small enough, no ?). Integrate this in grass is a good idea.
There is still a problem: this grid is not specified in the EPSG spec.
but only in the IGNF register (76 Kio) (see the tutorial for more
information).
As I report in the ticket 1219
<http://trac.osgeo.org/grass/ticket/1219>, proj integrate this (both the
grid and the register), but not GRASS. In fact, when you use the EPSG
location wizard, it would be very useful to be able to choose the IGNF
register (/usr/share/proj/IGNF) instead of the epsg. I tried to select
the IGNF file, but it doesn't work (may be a parse problem). I would
like to help the developers on this subject, but I don't really know how
to do more than an enhancement ticket.
Thibault.
Paul
name: Lambert Conformal Conic
proj: lcc
ellps: clark80IGN
lat_1: 46.8
lat_0: 46.8
lon_0: 0
k_0: 0.99987742
x_0: 600000
y_0: 2200000
towgs84: -168,-60,320,0,0,0,0
pm: paris
no_defs: defined
nadgrids: /usr/share/proj/ntf_r93.gsb
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