Perspective plane, the plane or surface on which the objects are delineated, or the picture drawn; the plane of projection; -- distinguished from the ground plane, which is that on which the objects are represented as standing. When this plane is oblique to the principal face of the object, the perspective is called oblique perspective; when parallel to that face, parallel perspective. -- Perspective shell (Zoöl.), any shell of the genus Solarium and allied genera. See Solarium.

Aërial perspective is the expression of space by any means whatsoever, sharpness of edge, vividness of color, etc. Ruskin.

Isometrical perspective, an inaccurate term for a mechanical way of representing objects in the direction of the diagonal of a cube. -- Perspective glass, a telescope which shows objects in the right position.