(cartography) Any systematic method of transforming the spherical representation of parallels, meridians and geographic features of the Earth's surface to a nonspherical surface, usually a plane.

(cartography) A mapping projection in which all great circle paths (on a sphere the shortest path between points) are shown as straight lines.

(mathematics) a branch of mathematics that investigates those properties of figures that are invariant when projected from a point to a line or plane

(film) A cinematic technique in which live action is filmed in front of a screen on which the background action or a background scene is projected. / tomographic reconstruction

plural of projective variety

(algebraic geometry) A Zariski closed subvariety of a projective space; the zero-locus of a set of homogeneous polynomials that generates a prime ideal.

(projective geometry) A line that includes a point at infinity; a line in a projective space; a projective space of dimension 1.

plural of projective line

plural of projective space

(geometry) A kind of geometrical space in which only relation(s) of incidence between points and lines matter; in such a space distances or angles do not matter and parallelism (as in an affine space) does not matter either.