[Geojson] Closure?

[Christopher Schmidt]

On Wed, Sep 12, 2007 at 10:19:29AM -0600, Tim Schaub wrote:
> Hey-
> 
> I like the idea of finalizing this.
> 
> >    4.1.3. The use of a "crs" member for EPSG:4326 is discouraged since the
> > default of not having a "crs" member would result in the same coordinate
> > values. 
> 
> Does anybody feel strongly about keeping this?  We're already pretty 
> weak in our handling of crs, and I think this point is a bit silly.  Are 
> we hoping that EPSG:4326 will go away if we discourage its use?

No. I don't care. I left it in because I thought someone else wrote it
and cared :) I'm just as happy to drop it.

> >    (4.1.2 is new.)
> >    
> >    4.1.2. To use a URL as a unique identifier to a coordinate reference 
> >           system, the "crs" member should have the following structure:
> >           "crs": {"type":"URL", "properties":{"url":
> >           "http://example.com/mysrs/"}. When used as a value,
> >           "URL" must be uppercased.         
> >       4.1.2.1. The specification does not offer any information on how
> >                to convert this URL into a spatial reference system: its
> >                use is inteded to provide users the ability to define
> >                their references outside the EPSG namespace *only*.
> 
> I like the idea of proposing a convention for crs definitions via url, 
> but I wonder if this should be a bit different.
>
> At some point, someone may want to know if they are getting WKT or proj4 
> text via a url.  The above recommendation doesn't really leave room for 
> differentiating.

What about:
 "The properties object should contain one member: "url", which
  specifies a URL for the spatial reference. An optional member, "type", is
  recommended, specifying the type of information available at the URL.
  This may be any string: suggestions are "proj4", "ogcwkt", "esriwkt",
  though others can be used.  Applications may use this "type" member to
  determine the type of information which is available at the URL."

"crs": {
  "type": "URL",
  "properties": { 
    "url": "http://spatialreference.org/ref/epsg/2001/proj4/",
    "type": "proj4"
  }
}  

Regards,
-- 
Christopher Schmidt
MetaCarta