# Converting Geocentric to Geodetic

I am only looking for a confirmation of what I believe to be true. If my explaination or conclusion is not accurate I would appreciate it if the reason can be explained to me.

Background Information:

I am attempting to research a method to calculate the Latitude, Longitude, and Height of a point on the planet earth given Range, Azimuth, and Elevation of a point relative to another point where the Lat, Long, and Altitude is known. I am going to be using a geophysical library that allows me to provide it a geocentric value and it will return a Latitude and Longitude and the Geodetic Datum.

Is WGS-84 is a valid datum for a Geocentric datum?
If I provide it a WGS-84 (X,Y,Z) point should it return a WGS-84 Latitude and Longitude?

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As a point of clarification: is the "geocentric value" a geocentric latitude or is it a Cartesian triple (x,y,z)? – whuber Aug 17 '11 at 16:05
The library documentation seems to indicate it would be a Cartesian triple. – Ramhound Aug 17 '11 at 16:09

Any geodetic datum is suitable for expressing coordinates in both geocentric and geodetic coordinate systems, so you should be fine using WGS 84.

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You might actually be asking the wrong question. Why would you want to convert to geocentric coordinates to do this? It sounds like your range, azimuth, and elevation are probably expressed in ellipsoidal terms--so you want a geodetic direct solution, on the ellipsoid. If you want to use geocentric coordinates, you will also have to express the azimuth and elevation angles in the geocentric frame.

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I need the Latitude and Longitude of a given point relative to a moving point in space. The Range, Azimuth, and Elevation values are also obviously being updated. What I wanted to confirm, and mkadunc has done, is if WGS-84 is a valid datum for both geocentric and godetic coorindates. – Ramhound Aug 18 '11 at 12:09

## protected by whuber♦Jul 10 '12 at 12:40

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