re: *Not a Licensed Surveyor

quote:

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Question for you (and anyone else who has surveyed land):

Do you take into account the "curvature" of the earth?

OR

Do you assume the land is flat?

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Depends on the technique being used and the end geodetic datum desired.

Survey grade GPS requires a datum shift from satellite datum, WGS-84 to local flat earth datum, normally expressed in State Plane or UTM coordinates. There’s a few intermediate calcs required to convert from satellite datum to the desired local datum, going from a curved sphere to local based flat earth coordinates.

“Flat Earth” survey datums can usually be done starting from a survey grade benchmark using a Total Station instrument in lieu of GPS.

Part of the surveyor’s skill set is knowing the science of Geodesy, which in some cases can be very complex. The earth is flattened at the poles, technically not a perfectly round sphere but egg shaped. It’s called an oblate spheroid.

That’s a simplified explanation of a complex subject known as Geodesy.