Which term refers to the process of transforming coordinates from a curved surface of the Earth to a flat map?

The term that describes the process of transforming coordinates from the curved surface of the Earth to a flat map is known as map projection. This technique involves mathematical transformations to represent three-dimensional surfaces (the Earth) onto two-dimensional formats (maps). Each map projection can distort distances, areas, angles, or shapes in different ways, and the choice of projection often depends on the purpose of the map and the area being mapped.

Map projections are essential in cartography, allowing for the creation of maps that can be used for navigation, education, and analysis in various geographic contexts. The accuracy of representation and the type of distortion introduced are critical aspects that map makers must consider when selecting a projection that suits their needs.

In contrast, the other terms pertain to different aspects of geographic and datums. A vertical datum refers to a base height reference for water flow, among other things, while geodetic datum provides a frame of reference for measuring geographic coordinates. A horizontal datum specifically relates to the coordinate system used for the horizontal positioning on the surface of the earth. While all these terms are related to geographic information systems, they do not address the specific transformation of coordinates from a curved surface to a flat map, which is the essence of map projection.