Integrate the IGNF register and the shift grid RGF93-NTF in grass

[lemaitret]

The IGNF registry and the shift grid are well integrated in proj, but not in grass.

More information on the way I found to well use these on the wiki : ​http://grass.osgeo.org/wiki/IGNF_Register

[lemaitret]

Excuse me, a better link is : ​http://grass.osgeo.org/wiki/IGNF_register_and_shift_grid_NTF/RGF93

Concerning the milestone, I think it affects every version.

[lemaitret]

People need maybe more description. I try to give them here.

First of all, I update the link I gave before : ​in English and ​in French

The IGNF registry is a document such as the EPSG specifications : it describes many projection parameters and give them an ID. The EPSG ID can be used in GRASS to create a location, but not the IGNF ID. On a Linux system the IGNF and the EPSG are in the folder: /usr/share/proj/ and they seem to be both well used by proj. GRASS manage to use the EPSG file, but not the IGNF.

It should be good to have the possibility to select and use the IGNF registry to define a location. It's currently not possible to well parse the IGNF registry with the location wizard.

A subproblem : the IGNF registry mentions the shift grid ntf_r93.gsb. To be used, this grid should be in the etc/nad/ folder of GRASS (on Linux and grass 6.4 : /usr/lib/grass64/etc/nad/).

It should be good to have a copy of the ntf_r93.gsb shift grid in the etc/nad/ folder of grass to use it.

Other links : IGNF registry : ​http://lambert93.ign.fr/fileadmin/files/IGNF ntf_r93.gsb shift grid : ​http://lambert93.ign.fr/fileadmin/files/ntf_r93.gsb

[neteler]

Indeed, GRASS 6.4 offers only:

alaska conus FL hawaii MD ntv1_can.dat nzgd2kgrid0005.gsb prvi stgeorge stlrnc stpaul TN WI WO

while proj-nad-4.7.0 offers:

alaska conus epsg esri esri.extra FL GL27 hawaii IGNF MD nad27 nad83 nad.lst ntf_r93.gsb ntv1_can.dat null nzgd2kgrid0005.gsb other.extra pj_out27.dist pj_out83.dist proj_def.dat prvi stgeorge stlrnc stpaul td_out.dist test27* test83* testvarious* TN WI WO world

Time to populate lib/proj/ with more nad files?

[neteler]

I don't know how to solved this issue. Just add more files to GRASS?

[vincent]

Replying to neteler:

I don't know how to solved this issue. Just add more files to GRASS?

We evoked this issue here for the last time : ​http://lists.osgeo.org/pipermail/grass-user/2013-August/068804.html You mentioned a possible new mechanism for grass to use these files (registers and grids) directly from proj directories (/usr/share/proj) instead of copies.

In the case of french projections, proj4 integrated IGNF and ntf_r93.gsb since version 4.6 or so.

[neteler]

lib/proj/ got an overhaul, see #2456.

Yet lacking is the use of PROJ's datum shift grid files directly rather than GRASS' local copy.

[neteler]

added ntf_r93.gsb and null.lla unless trac #2456 is solved in r68654

[neteler]

Replying to neteler:

added ntf_r93.gsb and null.lla unless trac #2456 is solved in r68654

and Makefile updated in r68655

[neteler]

Here how to test which files are used (expected: via GDAL/PROJ):

PROJ_DEBUG=ON CPL_DEBUG=ON m.proj proj_in="+init=epsg:4326" proj_out="+proj=longlat +datum=NAD27" coordinates=-100,40 -d

The debug messages contain the datum shift file usage information.

TODO: find test case for ntf_r93. Could be done by using the values from

​https://github.com/OSGeo/proj.4/blob/master/nad/testIGNF

within m.proj.

[neteler]

Ticket retargeted after milestone closed

[martinl]

All enhancement tickets should be assigned to 7.4 milestone.

[neteler]

Ticket retargeted after milestone closed

[martinl]

All enhancement tickets should be assigned to 7.6 milestone.

[martinl]

Ticket retargeted after milestone closed

[martinl]

Ticket retargeted after milestone closed