Vanishing point

"In graphical perspective, a vanishing point is a point in the picture plane π that is the intersection of the projections (or drawings) of a set of parallel lines in space on to the picture plane. When the set of parallels is perpendicular to the picture plane, the construction is known as one-point perspective and their vanishing point corresponds to the oculus or eye point O from which the image should be viewed for correct perspective geometry.Traditional linear drawings use objects with one to three sets of parallels, defining one to three vanishing points."