[Proj] Having a CRS added in the common libraries

Fri Nov 27 09:13:30 EST 2015

Continuing this thread on a related, but also orthogonal subject:

I would like to add support for old Danish systems to proj4.

Official, and public available, procedures exist for transforming these
systems to and from UTM/ETRS89. The problem is that the transformations are
given as high order polynomial coefficients, and a corresponding
implementation of a 2D Horner's scheme for high precision evaluation.

I suppose my first step would be to implement the Horner code in the proj4
code tree, and then perhaps adding the coefficients for the individual
transformations as external files, preferably in a widely recognized file
format, along with the grid shift files already used by proj. Perhaps then
either introducing a new qualifier for specifying the specific system or
overloading the +zone=... qualifier, essentially aiming at a proj syntax in
the general direction of:

proj +proj=horner +zone=s34j

or similar.

The reason we want to do this is that the official transformations
(included in out trlib software available over at
https://bitbucket.org/KMS/trlib) are used by geospatial software from
numerous providers, but given the ubiquity of proj, most users probably
already include proj in their code bases, hence making supporting old
Danish systems much easier - to some degree even automatically
accomplishable.

My colleagues and I are still just starting these considerations, so any
advice, thoughts and warnings would be most welcome.

Best regards

Thomas Knudsen
Senior Adviser, PhD
Danish Geodata Agency

2015-11-24 2:01 GMT+01:00 Stéphane Henriod <s at henriod.info>:

> That's kind of what I meant with "automatic" :-) that the newest version
> of EPSG is used when a new version of Proj4 is released
>
> So I got my answer, thanks boh of you!
>
> Cheers
>
> Stéphane
>
>
> Le lundi 23 novembre 2015, Even Rouault <even.rouault at spatialys.com> a
> écrit :
>
>> Le lundi 23 novembre 2015 16:45:20, Stéphane Henriod a écrit :
>> > Thanks for your answer!
>> >
>> > And if the change request is accepted, will it be automatically be
>> added to
>> > the Proj4 library?
>>
>> There's no such thing as "automatic" ;-) But if it is included in the EPSG
>> database then it should be available in proj.4/GDAL/libgeotiff when the
>> next
>> resynchronization with the EPSG database is done
>> (https://svn.osgeo.org/metacrs/geotiff/trunk/libgeotiff/csv/README)
>>
>> >
>> > Cheers
>> >
>> > Stéphane
>> >
>> > Le lundi 23 novembre 2015, Noel Zinn (cc) <ndzinn at comcast.net> a écrit
>> :
>> > > The following link is for a change request for the EPSG Dataset.  You
>> do
>> > > have to have an account, but that’s simple if you’ve never logged in
>> > > before.
>> > >
>> > > http://www.epsg.org/MakeChangeRequest
>> > >
>> > >
>> > > Noel Zinn, Principal, Hydrometronics LLC
>> > > +1-832-539-1472 (office), +1-281-221-0051 (cell)
>> > > noel.zinn at hydrometronics.com
>> > > <javascript:_e(%7B%7D,'cvml','noel.zinn at hydrometronics.com');>
>> (email)
>> > > http://www.hydrometronics.com (website)
>> > >
>> > > *From:* Stéphane Henriod <javascript:_e(%7B%7D,'cvml','s at henriod.info
>> ');>
>> > > *Sent:* Monday, November 23, 2015 5:40 AM
>> > > *To:* proj at lists.maptools.org
>> > > <javascript:_e(%7B%7D,'cvml','proj at lists.maptools.org');> ;
>> > > metacrs at lists.osgeo.org
>> > > <javascript:_e(%7B%7D,'cvml','metacrs at lists.osgeo.org');>
>> > > *Subject:* [Proj] Having a CRS added in the common libraries
>> > >
>> > > Dear all
>> > >
>> > > I am new to both lists (proj and metacrs) so my apologies for
>> > > cross-posting, I am not quite sure where my question belongs.
>> > >
>> > > I am working in the beautiful country of Kyrgyzstan, which happens to
>> > > have developed a new national geodetic framework. One of the outputs
>> is
>> > > a coordinate system (Kyrg06), divided in 5 zones.
>> > >
>> > > As far as I know, this coordinate system is not yet available in any
>> > > common library / software and is neither in the EPSG list.
>> > >
>> > > Is there any standard process to get a sort of international
>> recognition?
>> > > This system has been approved by the government and thus has a legal
>> > > validity in this country. But it will always be difficult to convince
>> > > people to use it as long as it's not readily available in the common
>> > > software (and thus in the underlying libraries). As a result, many GIS
>> > > users end up working with UTM or other not-so-optimal.
>> > >
>> > > Thanks a lot in advance for your hints and advice on this matter
>> > >
>> > > Cheers
>> > >
>> > > Stéphane
>> > >
>> > >
>> > > --
>> > >
>> > > "Le mot progrès n'aura aucun sens tant qu'il y aura des enfants
>> > > malheureux" -- Albert Einstein
>> > >
>> > > "Si les contacts avec les étrangers lui étaient permis, [le citoyen
>> > > ordinaire] découvrirait que ce sont des créatures semblables à
>> lui-même
>> > > et que la plus grande partie de ce qu'on lui a raconté d'eux est
>> fausse.
>> > > Le monde fermé, scellé, dans lequel il vit, serait brisé, et la
>> crainte,
>> > > la haine, la certitude de son bon droit, desquelles dépend sa morale,
>> > > pourraient disparaître" -- George Orwell ("1984")
>> > >
>> > > “When you travel, remember that a foreign country is not designed to
>> make
>> > > you comfortable. It is designed to make its own people comfortable."
>> --
>> > > Clifton Fadiman
>> > >
>> > > Photos de voyages, photos de montagne: http://www.henriod.info
>> > >
>> > > ------------------------------
>> > > _______________________________________________
>> > > Proj mailing list
>> > > Proj at lists.maptools.org
>> > > <javascript:_e(%7B%7D,'cvml','Proj at lists.maptools.org');>
>> > > http://lists.maptools.org/mailman/listinfo/proj
>>
>> --
>> Spatialys - Geospatial professional services
>> http://www.spatialys.com
>>
>>
>
> --
>
> "Le mot progrès n'aura aucun sens tant qu'il y aura des enfants
> malheureux" -- Albert Einstein
>
> "Si les contacts avec les étrangers lui étaient permis, [le citoyen
> ordinaire] découvrirait que ce sont des créatures semblables à lui-même et
> que la plus grande partie de ce qu'on lui a raconté d'eux est fausse. Le
> monde fermé, scellé, dans lequel il vit, serait brisé, et la crainte, la
> haine, la certitude de son bon droit, desquelles dépend sa morale,
> pourraient disparaître" -- George Orwell ("1984")
>
> “When you travel, remember that a foreign country is not designed to make
> you comfortable. It is designed to make its own people comfortable." --
> Clifton Fadiman
>
> Photos de voyages, photos de montagne: http://www.henriod.info
>
>
> _______________________________________________
> Proj mailing list
> Proj at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/proj
>
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