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

Hi Mathew,

Yes, it could be convenient 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 an
hypotethical 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)

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.

Thanks for posting,
regards,

Angel

Received on Monday, 13 October 2008 15:01:55 UTC