Refers to a perspective system that indirectly uses two vanishing points, but is empirical rather than scientific. It was primarily used in Western art prior to the codification of one-point perspective in the Renaissance. In bifocal perspective, two vanishing points are placed at the same height at the left and right margins of the picture plane. From these points are drawn diagonal lines to points along the bottom or top margins of the picture plane; the points at which these diagonal lines cross are used to draw a floor or ceiling grid which resembles a grid drawn with a single central vanishing point and gives the illusion of recession into space.
