What is used to correct for the curvature of the Earth in large-scale mapping?

In large-scale mapping, geodetic leveling is utilized to account for the curvature of the Earth. This technique involves measuring the elevation of points over large distances by establishing a network of benchmarks, which helps to establish an accurate representation of the Earth's surface.

Geodetic leveling is critical because it considers the Earth's shape (which is not a perfect sphere, but rather an oblate spheroid) when determining elevations and creating maps. It corrects for the variations in the Earth's gravity field and accounts for the curvature over long distances, ensuring that the elevations are accurate and reflect the true topography of the area being mapped.

Other methods listed do not specifically correct for the curvature of the Earth in the context of large-scale mapping. Trigonometric leveling involves using angles and distances but does not inherently correct for the Earth's curvature over extensive areas like geodetic leveling does. Geometric correction is a more general term that might refer to various adjustments in surveys and does not specifically encompass the methods required to correct for curvature. Physical leveling typically measures short distances and levels directly at the surface, which is not suitable for large-scale mapping scenarios where Earth's curvature becomes significant.