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

Fri Sep 2 23:17:53 PDT 2016

Are there other members of this discussion list who want to talk about the special topic described in Aarons mail (look below)?

If there are more than two it would make sense to start a separate group. 

Best regards,

Manfred

-----Original Message-----
From: "Aaron Racicot" <aaronr at z-pulley.com>
Sent: Friday, September 2, 2016 2:20pm
To: "Even Rouault" <even.rouault at spatialys.com>
Cc: discuss at lists.osgeo.org
Subject: Re: [OSGeo-Discuss] Detect and define the coordinate system of gis data with no projection information automatically

_______________________________________________
Discuss mailing list
Discuss at lists.osgeo.org
http://lists.osgeo.org/mailman/listinfo/discussYes... 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/
> 007480.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_
> EGGER_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
>
> --
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-- 
--------------------------------
Aaron Racicot
aaronr at z-pulley.com