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altitude reference system

From: Erik Wilde <dret@berkeley.edu>
Date: Mon, 22 Dec 2008 12:30:20 -0800
Message-ID: <494FF8DC.4040404@berkeley.edu>
To: "public-geolocation@w3.org" <public-geolocation@w3.org>


congratulations for the first draft! a nice holiday gift!

since my altitude comments so far have not made it into the draft, i am 
splitting them, because they are two different issues. or are they 
captured in some open issue list? if so, please provide a pointer.

"The altitude attribute denotes the height of the position, specified in 
meters above the [WGS84] ellipsoid. If the implementation cannot provide 
altitude information, the value of this attribute must be null."

there has to be some indication of whether this value takes the EGM96 
data account or not. both are valid choices of a client using GPS 
measurement, and will result in different values. a consumer of that 
data could even choose to retroactively apply the EGM96 correction, but 
for that, it needs to know whether the altitude provided through the API 
does already include this correction or not. i never received any 
replies to me previous emails about this issue, but technically 
speaking, if there is no flag indicating whether the altitude uses EGM96 
or not, there is simply not enough information about the reference 
system for this value.


Received on Monday, 22 December 2008 20:31:03 UTC

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