Introduction

In geodesy, a reference ellipsoid is a mathematically-defined surface that approximates the geoid, the truer figure of the Earth, or other planetary body. Because of their relative simplicity, reference ellipsoids are used as a preferred surface on which geodetic network computations are performed and point coordinates such as latitude, longitude, and elevation are defined.

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Configuring ellipsoids

An ellipsoid can be defined in Hydromagic using the following three parameters:

• Semi Major Axis ( a );
• Inverse Flattening ( f );
• Squared Eccentricity ( e2 ).

The eccentricity value is optional, because this value can be calculated using the semi major axis and the flattening using the following formula:

        
e2 = ( 2.0 * f ) - ( f * f )
      

Formula to calculate the eccentricity squared from the inverse flattening

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List of ellipsoids supported by Hydromagic