[GRASS-user] [GRASS-dev] nad grids storage

Vincent Bain bain at toraval.fr
Sun Aug 18 22:42:05 PDT 2013

Hello Markus,
thank you for the information,

all in all, IIUC this is basically a question of integrity of register
files. It sounds better that grass relies on PROJ.4 updates to handle
the correct files.

In my case PROJ.4 also provides the grid in /usr/share/proj, but it
seems not to be enough. When a projection is supposed to use the grid
(i.e. between two distinct geodetic systems), it is simply ignored if
absent from /usr/local/grass-XX.svn/etc/proj/nad/

This happens on correctly defined projection systems, for example I have
a location named L2e (Lambert II étendu), whith this PROJ_INFO file :
        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

On the other hand, I use a custom script to retrieve raster data from
the IGN wmts server. It is based on cs2cs and gdal_translate commands :
I noticed the issue is the same.


Le dimanche 18 août 2013 à 23:59 +0200, Markus Neteler a écrit :
> On Sun, Aug 18, 2013 at 10:55 AM, Vincent Bain <bain at toraval.fr> wrote:
> > Dear grass devs and users,
> > sorry for digging up this pretty old topic. It was about the end of my
> > initial message, see bellow (perhaps should I have opened a ticket for
> > it)
> Yes, perhaps that's needed.
> > The question was : is it possible to add the french nad grid to grids
> > provided by default in grass directories ?
> > Everytime I completely rebuild grass (after a make distclean) I have to
> > manually copy the ntf_r93.gsb file
> > into /usr/local/grass-XX.svn/etc/proj/nad/
> The file comes with PROJ.4 - on my Fedora box here:
> /usr/share/proj/ntf_r93.gsb
> We should figure out why it isn't used in your case.
> I observe that we still have the unsolved issue of using our "private"
> copy of these files:
> [neteler at oboe proj]$ ls -la WO*
> -rw-r--r--. 1 neteler gis 14111 Nov 25  2008 WO.lla
> [neteler at oboe proj]$ ls -la /usr/share/proj/WO*
> -rw-r--r--. 1 root root 11112 Feb 17 18:27 /usr/share/proj/WO
> [neteler at oboe proj]$ file WO*
> WO.lla: ASCII text
> [neteler at oboe proj]$ file /usr/share/proj/WO*
> /usr/share/proj/WO: data
> ... but with the date of 2008 and no more updates since then. I
> remember discussions about this some years ago.
> Due to changes in PROJ.4 we could no longer simply copy over the files.
> Now, it is time to revisit the mechanism and get rid of these copied
> files in favour of using those from PROJ.4.
> Thoughts?
> Markus

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