Surveying & Geomatics

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Earth Curvature Correction

Drop due to Earth's curvature over a sight distance (metres, K in km).

Formula

C = 0.0675 \, K^2

Variables

CCurvature correction (m)

KDistance (km)

Example

K=2 km: C = 0.0675×4 = 0.27 m

Did You Know?

Over long sights the Earth literally curves away, so levelling must correct for it — flat-earth math fails here.

surveying curvature levelling

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