# Grid to Ground Coordinate System Transformations

When working with civil engineering plans, it is necessary to work with scaled maps representing horizontal distances at ground level. Often it is also desirable to geo-reference the drawings to a standard coordinate system such as a State Plane Coordinate System or Universal Transverse Mercator coordinate system. This can present problems for engineering projects whose maps extend over a large geographical area, such as highway or railroad projects.

Map projections with an associated coordinate system and datum give cartographers the ability to map features on a curved and irregular earth on a flat surface, the map, while minimizing distortion of angles and distances. While cartographers and their clients can accept some map distortion, engineers usually need exact distances and angles. In order for civil engineers to utilize maps and government horizontal survey control points that are based on standard coordinate systems, there needs to be an understanding of the methods used to determine the coordinates of horizontal survey control points.