[Gdal-dev] Proposed Feature: Consumption of URL-based Spatial References

[Daniel Morissette]

I like the concept. I would rather read that we are using and extending 
support for an existing repository, than reading that we are creating 
our own repository, but I am not aware of an actual central repository 
somewhere that will accept user-contributions ... so I guess this is 
really filling a void.

Note that I am not an expert in OGC SRS and other projection 
authorities, so there may well be something that exists already and that 
I'm just not aware of.

Anyway, the extension seems simple and flexible enough to be extended to 
support other types of repositories someday, so I'm cool with it.

Daniel

Howard Butler wrote:
> All,
> 
> Chris Schmidt and I have been working on a website 
> <http://spatialreference.org> that reflects the EPSG spatial reference 
> codes database and user-contributed codes in a variety of output 
> formats.  The EPSG code database is never as up to date as you would 
> like, and we frequently tell people to hack their /usr/share/proj/epsg 
> database file with made up codes to support alternative projections.  If 
> we could consume URL-based spatial references with OSR, all that would 
> be required is someone adds the custom coordinate system definition to 
> the site and then everyone could refer to it at that location (hopefully 
> indefinitely).
> 
> As for the website itself, if it has uptake and people find it useful, 
> we will work to put it somewhere it can live for a very long time -- for 
> example OSGeo.  The source code (it's written in Django) will be made 
> available so anyone can stand up their own version of the site.
> 
> I would like to propose that an ImportFromUrl() method be added to 
> OSRSpatialReference that constructs a spatial reference given the 
> SetFromUserInput data retrieved at the given URL.  It would only need to 
> be as specific as that, and it wouldn't need to refer to 
> spatialreference.org.  Additionally, this mechanism could be used to 
> support GML SRS retrieval from URLs (which Frank mentioned was in the 
> spec) in the future.  This method would only be active if you have 
> included curl support, of course.  Maybe someday, if necessary, we do 
> some magical caching, but that'd be a premature optimization at this point.
> 
> Here's an example:
> 
> ogr2ogr -a_srs http://spatialreference.org/epsg/4326/proj4 -t_srs 
> http://spatialreference.org/user/6/proj4 world_borders.shp 
> world_borders_google.shp
> 
> Howard
> _______________________________________________
> Gdal-dev mailing list
> Gdal-dev at lists.maptools.org
> http://lists.maptools.org/mailman/listinfo/gdal-dev


-- 
Daniel Morissette
http://www.mapgears.com/