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1.  What are the units of measurement?  I think I could grasp
1368950/-4603950/4182550 more easily with a unit of measurement.

2.  I don't necessarily agree that it might make determination of our
centroid easier. An average in ECEF coordinates would easily give us a
point in the middle of the earth!   Don't know about you, but I prefer
sailing to digging :-)

Lu Abel

At 10:31 PM 7/24/2001 +0000, you wrote:
>Earth Centered Earth Fixed Cartesian coordinates.
>
>The origin is at the center of the earth. The positive z-axis goes through the
>N-pole. The positive x-axis goes through the equator and the Greenwich
>meridian. The y-axis completes the orthogonal system.
>
>Roughly speaking, ECEF coordinates are what you get when you use the formula
>given by  R. van Gent and multiply with the radius of the Earth in meters.
>
>   x = R * cos(lat) * cos(long)
>   y = R * cos(lat) * sin(long)
>   z = R * sin(lat)
>
>Strictly speaking, you must account for the spheroidal shape of the earth.
>
>These coordinates are easier to use in computers because all trigonometry
>becomes algebra. Your GPS reciever uses them internally, astronomers need them
>for exact topocentric reductions, or surveyors, for instance when they have to
>transform maps from one datum into another.
>
>There goes:
>
>Herbert Prinz (from 1368950/-4603950/4182550 ECEF)
>
>
>Dan Allen wrote:
>
> >
> > Just what are ECEF coordinates?  I've never heard of them.

   

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