perspective projection[pər′spek·tiv prə′jek·shən]
center of vision
central visual axis
cone of vision
a particular case of azimu-thal cartographic projections. A perspective projection can be obtained by projecting a sphere onto a picture plane tangent to a pole of the sphere; the projection is carried out by rays from an eye point lying on a line perpendicular to the plane and passing through the center of the sphere. Examples of perspective projections are the gnomonic projection, the stereographic projection, and external projections, where the eye point is outside the sphere at a finite distance, or at an infinite distance—in the latter case it is called orthographic projection.