A two-dimensional, planar coordinate system in which horizontal distance is measured along an x-axis and vertical distance is measured along a y-axis. Each point on the plane is defined by an x,y coordinate. Relative measures of distance, area, and direction are constant throughout the Cartesian coordinate plane. The Cartesian coordinate system is named for the French mathematician and philosopher Ren Descartes (1596-1650).
In imagery, a three-dimensional coordinate system where each axis is orthogonal, the scale in each direction is the same, and the reference for photogrammetry is earth stationary.