W3C home > Mailing lists > Public > public-geolocation@w3.org > June 2008

Re: The Geolocation API must provide location data in terms of a pair of latitude and longitude coordinates.

From: Erik Wilde <dret@berkeley.edu>
Date: Wed, 25 Jun 2008 10:09:13 -0700
Message-ID: <48627BB9.5070406@berkeley.edu>
To: public-geolocation@w3.org

Andrei Popescu wrote:
>> Futher, the draft arbitarily uses wgs84 for altitude, so it may be that
>> this is also intended to be used for latitude and longitude.
> That's true. I'll update the standard to reflect this. Note that it's
> not arbitrarily used, though: all GPS APIs we've looked at so far only
> use WGS84.

for elevation, wgs84 as a reference system is not sufficient. elevation 
depends on the geoid being used, which is an additional set of data 
required to better approximate the real shape of the earth with the 
model (wgs84 uses an ellipsoid, a mathematical simplification of the 
earth's shape). there is a surprisingly big difference between the pure 
ellipsoid model of wgs84, and the more accurate geoid model, up to 
almost 200m. so it is really important to be clear about the reference 
system being used.


and please forgive me if i am not entirely correct in what i am saying, 
i am not a GIS person. over the last year i have at least learned that 
location is a more complex concept than i first thought it would be.


Received on Wednesday, 25 June 2008 17:10:15 UTC

This archive was generated by hypermail 2.3.1 : Tuesday, 6 January 2015 20:33:49 UTC