[GeoJSON] Removing CRS from GeoJSON

[Martin Daly]

I'm happy with removing CRS altogether, and forcing "lon/lat relative to an ellipsoidal CRS based on the WGS84 datum". That matches most usage that I'm aware of (and KML).

I'd be wary of adding EPSG:3857 because it is the thin end of a very fat wedge.

Tim, I think the situation that we have at the moment is better than you describe, but not by much. We have "allow any CRS and axis order will always be lon/lat or easting/northing". We did that to avoid the burden of carrying around axis order knowledge. But it still has the burden on needing to know what EPSG:27700, or whatever, means. Web clients still have to get the WKT, Proj.4 string, etc, from that id (assuming that they can work with the result). So we dodged one bullet, but not the other, arguably more complex, one.

Here's a pull request of mine:

https://github.com/GeoJSONWG/draft-geojson/pull/3

Martin


From: geojson-bounces at lists.geojson.org [mailto:geojson-bounces at lists.geojson.org] On Behalf Of Tim Schaub
Sent: 15 May 2013 05:41
To: geojson at lists.geojson.org
Subject: [GeoJSON] Removing CRS from GeoJSON

So as to avoid hijacking Sean's thread, I'll start a new one here.

I'm in favor of restricting the allowed coordinate reference systems for GeoJSON objects to 1: latitude, longitude coordinates relative to an ellispoidal CRS based on the WGS84 datum.

I think the second best alternative would be to restrict to 2 CRS: CRS84 or EPGS:3857.

I don't like the "allow any CRS and let axis order follow the CRS" because I think it either reduces interoperability or imposes an unreasonable burden on web clients (I don't know of a good web service - or really want to depend on one - that provides axis order information for arbitrary CRS URN, and the table is too big to ask every client to carry around).

I apologize for having missed earlier "discussion" [1]. I haven't dug down to that epoch in my inbox yet.

And I'm in favor of the proposed RFC to IETF [2].

https://github.com/GeoJSONWG/draft-geojson/pull/2

[1] http://lists.geojson.org/pipermail/geojson-geojson.org/2013-April/000712.html
[2] http://lists.geojson.org/pipermail/geojson-geojson.org/2013-April/000713.html

Tim

PS - Do the build artifacts (xml, txt, etc) need to be in the repo? If so, can someone update the README.md with detail on building them?

PPS - Mildly curious what it means to be "commented out" as an author. I do see a comment that suggests authors should be asked if they are willing to be authors. Happy to entertain that question.




--
Tim Schaub
OpenGeo http://opengeo.org/
Expert service straight from the developers.
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