Ellipse Dialog

If necessary, you can edit the values used to compute the ellipse. These values affect the computations between grid coordinates and geodetic positions.

Name

Enter the name you wish to give the ellipse. This is just for your reference and does not affect the computations.

Semi-Major, Semi-Minor, Reciprocal Flat, Eccentricity Squared

Enter the ellipse values. Other ellipse values that are dependent on a value you enter are recomputed and displayed for you.

Close

Accept the changes and return.

If you are transforming a survey, the target ellipse values are stored with the survey in the TRV file. All future transformations between grid and geodetic positions will be based on these ellipse values.

Ellipsoid Parameters

Datum	Ellipsoid	Semi-Major (m)	Reciprocal Flattening
NAD 27	Clark 1866	6378206.4	294.9786982
NAD 83	GRS 80	6378137.0	298.257222101
WGS 84	WGS 84	6378137.0	298.257223563

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