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Plane versus geodetic surveying

Short answer

Surveying determines relative positions of points and maps them. Plane surveying neglects earth's curvature for areas up to about 250 km², using plane trigonometry and ordinary accuracy. Geodetic surveying considers curvature for larger areas, uses spherical trigonometry, and attains high precision.

Define surveying. Differentiate between plane surveying and geodetic surveying.

Surveying is the art and science of determining the relative positions of points on, above or below the earth's surface by measuring distances, directions (angles) and elevations, and of representing them on a map or plan to a suitable scale. It is also used to set out (locate) planned works on the ground.

Difference between plane and geodetic surveying

BasisPlane surveyingGeodetic surveying
Shape of earthTaken as a plane; curvature neglectedEarth taken as a spheroid; curvature considered
Level surfaceTreated as a straight lineTreated as a curved line (arc)
Area coveredSmall, up to about 250 km2^2Large, above about 250 km2^2
Triangle anglesSum is exactly 180∘180^\circSum exceeds 180∘180^\circ (spherical excess)
MathematicsPlane trigonometrySpherical trigonometry
AccuracyOrdinary accuracyHigh accuracy; precise instruments
PurposeLocal works: roads, buildings, canalsControl points, national mapping, large projects
Cost and timeLowHigh, needs skilled staff
Geodetic dataNot neededLatitude, longitude and azimuth are determined

In short, the two methods differ in whether the earth's curvature is considered or neglected; this depends on the size of the area and the accuracy required.

✓ Answer checked by Claude Opus 5.5 (high effort)

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