Definitions for

**"Perspective projection"**A simple geometric map projection in which the surface of the Earth is transformed to one of three developable surfaces; the plane, cylinder, or cone. Most map projections can be described and categorized according to from which geometric surface they are derived. The point of perspective of most projections is at the centre of the Earth. However, with the planar family of map projections the point of perspective may also be a location opposite to the point of tangency or from an external point, as if the Earth were viewed from outer space.

(n.) The process of projecting an image from the 3-D view volume to the 2-D graphics display with projector lines that converge at the eye point. Objects appear to diminish if they are further from the eye point.

Projection produced by projecting straight lines radiating from a selected point (or from infinity) through points on the surface of a sphere or ellipsoid and then onto a tangent or secant plane. Other perspective maps are projected onto a tangent or secant cylinder or cone by using straight lines passing through a single axis of the sphere or ellipsod. Also called geometric projection