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Re: RFC 5870 - A Uniform Resource Identifier for Geographic Locations ('geo' URI)

From: Ed Parsons <eparsons@google.com>
Date: Wed, 22 Jul 2015 09:16:16 +0000
Message-ID: <CAHrFjcnYFRt9dQQBvy=QYUN=840FeztB7cX=a8Fh9cAtpXZFyw@mail.gmail.com>
To: Joshua Lieberman <jlieberman@tumblingwalls.com>, simon.cox@csiro.au
Cc: public-sdw-wg@w3.org
Yes matters sometimes.. to some people.. It is equally a generalisation to
say that geodetic details are relevant to everyone using global coordinates
on the web !

Ed


On Wed, 22 Jul 2015 at 03:01 Joshua Lieberman <jlieberman@tumblingwalls.com>
wrote:

> An excellent cautionary tale. For example, the 3D default coordinate
> system is cited as EPSG:4979, with optional elevation relative to the WGS84
> geoid. However, 4979 elevation is relative to the WGS84 ellipsoid, not the
> geoid the RFC cites. There is a defined WGS84 gravimetric geoid (EGM96)
> that varies from the ellipsoid by around +/-100m over the earth, and is
> approximated by a coarse coverage in most modern GPS units while neglected
> in older ones. Unfortunately the geodetic details matter.
>
> -Josh
>
>
> On Jul 21, 2015, at 8:08 PM, simon.cox@csiro.au wrote:
>
> Just became aware of this (via the GeoJSON list)
>
> https://tools.ietf.org/html/rfc5870#section-3.4.5
>
> I’ve added it to the BP ref list
> https://www.w3.org/2015/spatial/wiki/BP_References
>
> Simon
>
>
> --


*Ed Parsons* Geospatial Technologist, Google

Mobile +44 (0)7825 382263
www.edparsons.com @edparsons
Received on Wednesday, 22 July 2015 09:16:57 UTC

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