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What is Orthometric Correction?

We know that earth flattens in the polar direction and this curvature of earth is responsible for the departure of horizontal line from a level surface. To counter this error, orthometric corrections is applied.

This departure in feet, Cf is calculated as

Cf= 0.667M2=0.0239F2

This departure in meters, Cm is calculated
Cm =0.0785K 2

where M = distances in miles from the point of tangency to the earth.
F= distances in thousands of feet from the point of tangency to the earth.
K = distances in kilometers from the point of tangency to the earth.

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Kanwarjot Singh

Kanwarjot Singh is the founder of Civil Engineering Portal, a leading civil engineering website which has been awarded as the best online publication by CIDC. He did his BE civil from Thapar University, Patiala and has been working on this website with his team of Civil Engineers.

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One comment on "What is Orthometric Correction?"

Jerry Mahun says:

This is NOT the orthometric correction. The equation and discussion are for earth curvature – how much a spherical surface departs from a tangential straight line as distance increases.
The orthometric correction an elevation correction due to the effect of gravity and centrifugal force on equipotential surfaces. These surfaces are flattened at the poles and expanded at the equator. A “constant” elevation is an equipotential surfaces. The physical distance between two elevations gets shorter as we approach the poles. The amount it shortens, which depends on the distance surveyed, is the orthometric correction.

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