proj-datumgrid-1.4 issued

[Frank Warmerdam]

Folks,

I have uploaded a new version of the datum grid shift file collection that
includes the ntf_r93.gsb shift file.  Richard, perhaps you could more fully
explain how this grid shift file works?

   http://download.osgeo.org/proj/proj-datumgrid-1.4.zip

Best regards,
--
---------------------------------------+--------------------------------------
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[Richard Greenwood]

On Mon, Jul 21, 2008 at 7:59 PM, Frank Warmerdam <[hidden email]> wrote:
> Folks,
>
> I have uploaded a new version of the datum grid shift file collection that
> includes the ntf_r93.gsb shift file.  Richard, perhaps you could more fully
> explain how this grid shift file works?

I wish I could, but I'm still struggling with the .lla files!

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[Frank Warmerdam]

Richard Greenwood wrote:
> On Mon, Jul 21, 2008 at 7:59 PM, Frank Warmerdam <[hidden email]> wrote:
>> Folks,
>>
>> I have uploaded a new version of the datum grid shift file collection that
>> includes the ntf_r93.gsb shift file.  Richard, perhaps you could more fully
>> explain how this grid shift file works?
>
> I wish I could, but I'm still struggling with the .lla files!

Rich,

Sorry, I actually mean Richard Didier who added this .gsb file in PROJ.  :-)

I should have been more specific.

Best regards,
--
---------------------------------------+--------------------------------------
I set the clouds in motion - turn up   | Frank Warmerdam, [hidden email]
light and sound - activate the windows | http://pobox.com/~warmerdam
and watch the world go round - Rush    | President OSGeo, http://osgeo.org

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[Paul Kelly]

On Tue, 22 Jul 2008, Frank Warmerdam wrote:

> Richard Greenwood wrote:
>> On Mon, Jul 21, 2008 at 7:59 PM, Frank Warmerdam <[hidden email]>
>> wrote:
>>> Folks,
>>>
>>> I have uploaded a new version of the datum grid shift file collection that
>>> includes the ntf_r93.gsb shift file.  Richard, perhaps you could more
>>> fully
>>> explain how this grid shift file works?
>>
>> I wish I could, but I'm still struggling with the .lla files!
>
> Rich,
>
> Sorry, I actually mean Richard Didier who added this .gsb file in PROJ.  :-)

I imagine this would be similar to my france.gsb file to convert between
the French NTF and RGF93 datums, documented in detail here:
http://www.stjohnspoint.co.uk/gis/france.htm
so perhaps that page would be of interest?

Paul

(BTW I never pressed to have it included in GRASS or PROJ.4 as I wasn't
sure about the licence/legal status of the tables I derived it from.)
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[RICHARD Didier]

Le Mardi 22 Juillet 2008 19:28, Paul Kelly a écrit :

> On Tue, 22 Jul 2008, Frank Warmerdam wrote:
> > Richard Greenwood wrote:
> >> On Mon, Jul 21, 2008 at 7:59 PM, Frank Warmerdam <[hidden email]>
> >>
> >> wrote:
> >>> Folks,
> >>>
> >>> I have uploaded a new version of the datum grid shift file collection
> >>> that includes the ntf_r93.gsb shift file.  Richard, perhaps you could
> >>> more fully
> >>> explain how this grid shift file works?
> >>
> >> I wish I could, but I'm still struggling with the .lla files!
> >
> > Rich,
> >
> > Sorry, I actually mean Richard Didier who added this .gsb file in PROJ.
> > :-)
>

It's me !-)

> I imagine this would be similar to my france.gsb file to convert between
> the French NTF and RGF93 datums, documented in detail here:
> http://www.stjohnspoint.co.uk/gis/france.htm
> so perhaps that page would be of interest?

Well, there is a difference between your grid and our : while your grid is
correct and our has been built using the same overall process, our grid
ensure the centimeter precision (they are something like 2 more iterations
when computing the grid's nodes).

You can keep our page on by just informing users the difference in precision
between your grid and our.

>
> Paul
>
> (BTW I never pressed to have it included in GRASS or PROJ.4 as I wasn't
> sure about the licence/legal status of the tables I derived it from.)

No problem for the licence/legal status : the original text file found on
IGN's web side is public data. A lot of GIS editors have been using it
directly to implement the projection usign this grid. So, feel free to use by
keeping in mind the above point on precisions.

All the best,

didier
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--
Didier RICHARD, chef du pôle technique Géoportail pour l'IGN
Institut Geographique National           tel: [phone]
2/4 Avenue Pasteur                       fax: [phone]
F-94165 St-Mande Cedex                e-mail: [hidden email]


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[Paul Kelly]

On Wed, 23 Jul 2008, Richard didier wrote:

> Le Mardi 22 Juillet 2008 19:28, Paul Kelly a écrit :
[...]
>> I imagine this would be similar to my france.gsb file to convert between
>> the French NTF and RGF93 datums, documented in detail here:
>> http://www.stjohnspoint.co.uk/gis/france.htm
>> so perhaps that page would be of interest?
>
> Well, there is a difference between your grid and our : while your grid is
> correct and our has been built using the same overall process, our grid
> ensure the centimeter precision (they are something like 2 more iterations
> when computing the grid's nodes).

Hi Didier,
That's great! It's really good to have an "official" NTv2 file and it
means I can now retire mine. I've added a note to the page recommending
to use your new more precise file.

Thanks,

Paul

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[Mikael Rittri]

Hello,
In July 2008, Richard Didier wrote about the ntf_r93.gsb file
( http://lists.maptools.org/pipermail/proj/2008-July/003590.html ).

I just wondered what would be the best way to give a web link
to this file.  I thought it had been published on the www.ign.fr web
site,
but I cannot find it there.  So maybe the file is just a semi-official
service to the open source community?  And the canonical web link
should go to the PROJ.4 site?

Same question for the file Dictionaries/Spain/sped2et-2005.gsb
in the CS-Map distribution (http://trac.osgeo.org/csmap).
I cannot find it by googling for

  "sped2et-2005.gsb" site:www.ign.es

Would the canonical link go to the CS-Map site?

Best regards,
--
Mikael Rittri
Carmenta AB
SWEDEN
www.carmenta.com
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[Cuinet Jérôme]

The best link would be http://lambert93.ign.fr/index.php?id=30#c71

For spain files, it may be the same thing, a distribution on an annexe site,
as lambert93.ign.fr despite of ign.fr

Best regards,

Jérôme Cuinet
----- Original Message -----
From: "Mikael Rittri" <[hidden email]>
To: <[hidden email]>; "PROJ.4 and general Projections Discussions"
<[hidden email]>
Cc: <[hidden email]>
Sent: Wednesday, September 09, 2009 1:34 PM
Subject: [Proj] Official source for some NTv2 files?

> Hello,
> In July 2008, Richard Didier wrote about the ntf_r93.gsb file
> ( http://lists.maptools.org/pipermail/proj/2008-July/003590.html ).
>
> I just wondered what would be the best way to give a web link
> to this file.  I thought it had been published on the www.ign.fr web
> site,
> but I cannot find it there.  So maybe the file is just a semi-official
> service to the open source community?  And the canonical web link
> should go to the PROJ.4 site?
>
> Same question for the file Dictionaries/Spain/sped2et-2005.gsb
> in the CS-Map distribution (http://trac.osgeo.org/csmap).
> I cannot find it by googling for
>
>  "sped2et-2005.gsb" site:www.ign.es
>
> Would the canonical link go to the CS-Map site?
>
> Best regards,
> --
> Mikael Rittri
> Carmenta AB
> SWEDEN
> www.carmenta.com
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> Proj mailing list
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>

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[Melita Kennedy]

>Date: Wed, 9 Sep 2009 23:23:35 +0200
>From: Cuinet J?r?me <[hidden email]>
>Subject: Re: [Proj] Official source for some NTv2 files?
>To: "PROJ.4 and general Projections Discussions"
> <[hidden email]>, <[hidden email]>
>Cc: [hidden email]
>
>The best link would be http://lambert93.ign.fr/index.php?id=30#c71
>
>For spain files, it may be the same thing, a distribution on an annexe site,
>as lambert93.ign.fr despite of ign.fr
>
>Best regards,
>
>J?r?me Cuinet
>----- Original Message -----
>From: "Mikael Rittri" <[hidden email]>
>To: <[hidden email]>; "PROJ.4 and general Projections Discussions"
><[hidden email]>
>Cc: <[hidden email]>
>Sent: Wednesday, September 09, 2009 1:34 PM
>Subject: [Proj] Official source for some NTv2 files?
>
>
>> Hello,
>> In July 2008, Richard Didier wrote about the ntf_r93.gsb file
>> ( http://lists.maptools.org/pipermail/proj/2008-July/003590.html ).
>>
>> I just wondered what would be the best way to give a web link
>> to this file.  I thought it had been published on the www.ign.fr web
>> site,
>> but I cannot find it there.  So maybe the file is just a semi-official
>> service to the open source community?  And the canonical web link
>> should go to the PROJ.4 site?
>>
>> Same question for the file Dictionaries/Spain/sped2et-2005.gsb
>> in the CS-Map distribution (http://trac.osgeo.org/csmap).
>> I cannot find it by googling for
>>
>>  "sped2et-2005.gsb" site:www.ign.es
>>
>> Would the canonical link go to the CS-Map site?
>>
>> Best regards,
>> --
>> Mikael Rittri
>> Carmenta AB
>> SWEDEN
>> www.carmenta.com

Mikael,

It looks like the Spanish files (there's one for the Balearic Islands too) are here:

http://www.fomento.es/mfom/lang_castellano/direcciones_generales/organos_colegiados/csg/etrs89/default.htm

Melita

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[Mikael Rittri]

 
Many thanks to Jérôme, Melita, and Norm.

Melita wrote:
> It looks like the Spanish files (there's one for the Balearic Islands too) are here:
> http://www.fomento.es/mfom/lang_castellano/direcciones_generales/organos_colegiados/csg/etrs89/default.htm

An excellent find. I will just add that these files seem to be newer
than the SPED2ET.gsb file that Norm mentioned.

The Spanish title for the files means

    "GRID_SHIFT_FILE V2009: Grid Datum to shift
     between ED50 and ETRS89 in NTv2 format --- 317 KB"

(Google Translate plus some word shuffling by me),
and the files have the date 3 March, 2009.  
They also have new names,
    R2009V9.gsb
and
    BALR2009.gsb

There is some documentation in Spanish under the heading
    "Real Decreto 1071/2007..."
(Google Translate says "Royal Decree 1071/2007 of 27 July,
 regulating the official geodetic reference system in Spain").

Thanks again,
--
Mikael Rittri
Carmenta AB
www.carmenta.com

-----Original Message-----
From: [hidden email] [mailto:[hidden email]] On Behalf Of Melita Kennedy
Sent: den 11 september 2009 07:49
To: [hidden email]
Subject: Re: [Proj] Official source for some NTv2 files?

[--- text deleted ---]
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[hamish-2]

will a summary of all these be posted to the proj4 wiki site?

http://trac.osgeo.org/proj/


?,
Hamish



     
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[Mikael Rittri]

Hamish wrote:
> will a summary of all these be posted to the proj4 wiki site?

Well, I am not so experienced in creating new wiki pages, but here
is the summary in wiki-format.  Maybe someone can put it on
the Proj4 wiki, and perhaps straighten out some of the question marks.

=== Grid Shift Files in NTv2 format. ===
Links to some NTv2 files can be found below. For most of them, I think
the target datum
is something that is equivalent to '''WGS84''' on the 1 meter level.
(For example, the Spanish
files convert the old datum '''ED50''' to '''ETRS89''', whose main
difference from '''WGS84'''
is due to continental drift.) However, note that the Swiss file has a
national target datum.

The word "Official" after the link, means that the NTv2 files are the
officially recommended way
to convert coordinates.  "Semi-official" means that there is a more
official way, but the
NTv2 files have been prepared by a National Mapping Agency as an
alternative way (perhaps
slightly less precise.)  "Official?", with a question mark, means I
don't know whether
the files are Official or just Semi-official.
  * [http://www.icsm.gov.au/icsm/gda/gdatm 
     Australia] Official.
  * [http://www.geod.nrcan.gc.ca/tools-outils/ntv2_e.php 
     Canada] Official, free for end users, but may not be redistributed
freely.
  * [http://lambert93.ign.fr/index.php?id=30#c71 
     France] Semi-official.
  *
[http://crs.bkg.bund.de/crseu/crs/descrtrans/BeTA/de_dhdn2etrs_beta.php 
  Germany] Official?
  * [http://lists.maptools.org/pipermail/proj/2006-November/002658.html 
  Great Britain] Files constructed by Paul Kelly.  Very good (on
land), but not official.
  *
[http://www.linz.govt.nz/geodetic/software-downloads/gd2000it/index.aspx
     New Zealand] Official.
  *
[http://www.fomento.es/mfom/lang_castellano/direcciones_generales/organo
s_colegiados/csg/etrs89/default.htm
     Spain] Official?
  *
[http://www.swisstopo.admin.ch/internet/swisstopo/en/home/topics/survey/
lv03-lv95/chenyx06/distortion_grids.html
        Switzerland] Semi-official. (Goes only from '''CH1903''' to
'''CH1903+''', so a final 3-parameter shift is needed to reach
'''WGS84''').


--
Mikael Rittri
Carmenta AB
SWEDEN
www.carmenta.com
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