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

RE: Spec is missing 'declination' - body's current pointing angle above horizon

From: Machin, Angel, VF-ES (amachin) <angel.machin@vodafone.com>
Date: Mon, 13 Oct 2008 16:45:13 +0200
Message-ID: <11497DA0013FB9499B007FC17A24ACB702148CD4@ESM9-MXMB01.vf-es.internal.vodafone.com>
To: <public-geolocation@w3.org>
Hi Mathew,

 

Yes, it could be a good idea to have this additional variable that
together with the heading could be used to calculate a 3D vector
corresponding with the device's orientation. It could be easily read
from the device's accelerometers if available. As an example, it could
be useful for a hypothetical sky-map application. 

 

However, I think that in navigation and astronomy the right term for
this value would be elevation angle or altitude. If you take the
Horizontal Coordinate System that uses the observer's horizon as the
reference plane, the altitude gives you this value. So when altitude is
0 degrees, you are pointing towards the horizon while with an altitude
of 90 degrees you are pointing the zenith
(http://en.wikipedia.org/wiki/Horizontal_coordinate_system
<http://en.wikipedia.org/wiki/Horizontal_coordinate_system> )

 

The declination is used in the equatorial coordinate system which is 2D,
and uses a projection of the earth as the fundamental plane. So
declination in this system would be equivalent to the latitude. 

 

Regards,

 

Angel

 

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Received on Monday, 13 October 2008 14:45:58 UTC

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