[sr.org] [OSGeo-Discuss] Detect and define the coordinate system of gis data with no projection information automatically

Fri Sep 2 13:33:18 PDT 2016

Luis, Manfred,

As I said earlier, I will start to check up formulae on wikipedia and now
also on http://proj4.org/projections/index.html.
This is a valuable work.

But we also need to talk about the repo proj format.
Before, as many tolds us, it seems that many registry - that already exists
- do have reference updates we need to respect.
May we start to enumerate all these tools ?

- spatialreference
- epsg.io
- projections/index.html
- https://github.com/ebrelsford/projestions#api
- http://www.epsg-registry.org/
- ... (may be others ?)

The aim is that they already think about a great format before us. So what
is the format they use, and how ?
(if this made sens for you).

Regards,
Julien

2016-09-02 20:20 GMT+02:00 Aaron Racicot <aaronr at z-pulley.com>:

> Yes... this conversation has kind of morphed.
>
> The projfinder.com idea started as a side project in collaboration with
> the cugos.org group.  The idea is simple...
>
> Given a dataset with an unknown projection:
>
> 1) Have the end user give a "rough estimate" of the geo-location of the
> dataset by centering a map on that location
> 2) Have the user give one X,Y pair of coordinates from the dataset
>
> From this information we can try to "guess" the projection of the data.  I
> presented this idea at FOSS4G NA 2013 and the slides are located here:
>
> http://media.reprojected.com/presentations/Presentations/
> foss4g-na-2013/projfinder.pdf
>
> Manfred has taken this concept and created a desktop tool with a similar
> goal... help people determine the projection of existing data using some
> spatial context given by the user.
>
> It is true that this idea requires a spatial database of projections (and
> bounding boxes of projection validity).
>
> The test server that this old (circa 2013) projfinder service is running
> on is small and not meant to be a production system.  It is based on EPSG
> data loaded into postgis to do the processing.
>
> For clarity it seems to me we have multiple conversations going (and
> probably can migrate them someplace other than the general OSGeo Discuss
> list):
>
> 1) Discussion of open and authoritative projection databases
> 2) Discussion of services built around these databases
> 3) A more narrow conversation on the validity of a service like
> projfinder.com and its future (where it is served, etc).
>
> Anyway, I have not really chimed in as I am not so involved in #1 and
> #2... but if people want to take a conversation about #3 elsewhere... I am
> happy to follow.
>
> Aaron
>
>
>
>
>
> On Fri, Sep 2, 2016 at 12:50 AM, Even Rouault <even.rouault at spatialys.com>
> wrote:
>
>> Foks,
>>
>> I read through the emails of this thread and I'm still not sure to
>> understand
>> what the exact focus would be. It seems it might go beyond the title of
>> this
>> email thread.
>>
>> Is it about documentation about projections ? If so, I guess improving
>> proj.4
>> documentation could be appreciated. There has been a new commit just last
>> night ( http://lists.maptools.org/pipermail/proj/2016-September/0074
>> 80.html )
>> to add the chart of each projection :
>> http://proj4.org/projections/index.html . There are only images
>> extracted from
>> ftp://ftp.remotesensing.org/proj/OF90-284.pdf for now but that would be
>> great
>> to extend them with formulas, etc...
>>
>> Is it about having a catalog of spatial reference systems (and all related
>> information: projections, projection parameters, ellipsoids, datums, prime
>> meridians, area of use, transformations, etc...) ? Then there are
>> different
>> projects already tackling that. For example GDAL starts with the EPSG
>> catalog
>> + some algorithms to detect one of the many datum shifts to WGS84 (this
>> part
>> is controversial and could/should be improved), and that is the source
>> from
>> which the proj.4 'espg' catalog (the whole process is documented at
>> https://svn.osgeo.org/metacrs/geotiff/trunk/libgeotiff/csv/README). This
>> process
>> is a bit cumbersome and we had some discussions last year about perhaps
>> adopting a SQLite3 database instead (see thread starting at
>> https://lists.osgeo.org/pipermail/metacrs/2015-August/000846.html) : this
>> hasn't made progress yet.
>> GDAL has also a few extra catalogs from (somewhat old) ESRI definitions,
>> and
>> other vendors. There are also catalogs for SRS of other planets :
>> https://trac.osgeo.org/gdal/ticket/6623 (interestingly Peter Baumann
>> mentionned that the EPSG service might host this catalog in the future)
>> A tricky part about all this catalogs is the intellectual property behind
>> as
>> there are often not completely "free" in the meaning we generally give to
>> that
>> term for software (redistribution is OK, but most often modifying
>> definitions
>> is not allowed). But beyond that, as raised by Carl Reed, adding new
>> spatial
>> reference system definitions, or editing existing ones, is something that
>> needs
>> some form of validation at some point (unless you decide that anyone can
>> modify anything, but that opens the door to voluntary or unvoluntary
>> mess). It
>> is similar to when someone submits a patch/pull request for code: someone
>> needs to make a decision if it is appropriate or not.
>>
>> You've also identified spatialreference.org (now somewhat abandonned due
>> to
>> lack of volunteer) or epsg.io as online catalogs. I see also
>> https://github.com/ebrelsford/projestions#api that has been mentionned.
>> Perhaps one or several of them of those could be used as the base to build
>> something new above ?
>>
>> Probably that the MetaCRS list could be a more appropriate and focused
>> place
>> to hold such further discussions ?
>> https://lists.osgeo.org/mailman/listinfo/metacrs
>>
>> Unrelated: I read a few confusions in this thread with "OSGeo members" vs
>> "OSGeo charter members". Quickly summarizing
>> http://www.osgeo.org/membership:
>> anyone can declare himself as a OSGeo member by registering himself on
>> https://wiki.osgeo.org/wiki/Special:RequestAccount . OSGeo charter
>> members are
>> members who are elected, for the only additional purpose of electing the
>> OSGeo
>> boards. There are also OSGeo participants who are anyone that takes part
>> to
>> OSGeo related activities. Projects are generally open to contributions
>> from
>> anyone, with some kernel/PSC (not necessarily made of charter members)
>> taking
>> the main decisions.
>>
>> Best regards,
>>
>> Even
>>
>> > Hello,
>> >
>> > At FOSS4G 2016 in Bonn i talked with Venkatesh Raghavan about my poster
>> > presentation "SHAPEFILE PROJECTIONFINDER". URL to poster:
>> > http://www.egger-gis.at/app/download/13175253496/POSTER_EGGE
>> R_FOSS4G.pdf?t
>> > =1469787116
>> >
>> > He recommended to start a discussion in this mailing list about the
>> topic
>> > mentioned in the mail subject.
>> >
>> > I also talked in Bonn with Petr Pridal about http://epsg.io. Some days
>> > before Bonn i wrote emails to Aaaron Racicot and the mailing list of
>> > http://spatialrefrence.org.
>> >
>> > Please read first carefully on my website, what i plan to do:
>> >
>> > http://www.egger-gis.at/shapefile-projectionfinder/
>> >
>> > There are two problems to solve before tools like SHAPEFILE
>> > PROJECTIONFINDER can be developed as a sustainable solution:
>> >
>> > 1. Until today there is no stable free service running like
>> > www.projfinder.com by Aaron Racicot, which can be used by all
>> developers.
>> >
>> > 2. Until today there is no open source database which includes all
>> > coordinate system with epsg-code and additionally user and esri definded
>> > grids.
>> >
>> > There are open source solutions like:
>> >
>> > - spatialrefrence.org
>> > - epsg.io
>> >
>> > But in the detail both solutions have problems to update their database
>> > with low costs.
>> >
>> > Maybe OSGeo can promote a stable service with load balancing on the
>> base of
>> > an existing solution like epsg.io including Aarons idea?
>> >
>> > Maybe organisation like UN, a university or EU (INTERREG) are possible
>> > project partners/sponsors for such a solution?
>> >
>> > The goal is: Tools like SHAPEFILE PROJECTIONFINDER, a Q-GIS-Plugin or a
>> > mobile application can use a stable free gis-service updated daily and
>> > help gis users to solve projection troubles faster. I think gis users
>> > working not everyday with gis will be happy about this solutions?
>> >
>> > What do you think about my idea?
>> >
>> > Best regards,
>> >
>> > Manfred Egger
>> >
>> > Alois-Schrott-Str. 34
>> > 6020 Innsbruck
>> > Austria
>> >
>> > Web: http://egger-gis.at
>> >
>> > _______________________________________________
>> > Discuss mailing list
>> > Discuss at lists.osgeo.org
>> > http://lists.osgeo.org/mailman/listinfo/discuss
>>
>> --
>> Spatialys - Geospatial professional services
>> http://www.spatialys.com
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>>
>
>
>
> --
> --------------------------------
> Aaron Racicot
> aaronr at z-pulley.com
>
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