linear perspective

An artistic technique {linear perspective}| depicts scenes as they appear to human eyes.

picture plane

Imagine standing in front of a window looking onto a street or yard. Window is a vertical plane, parallel to line between your eyes. Straight lines of sight go from eye to scene points. See Figure 1.

Lines go through window at unique points. Artists paint scene-point color at the unique point in the picture plane. See Figure 2. Farther scene points have higher picture-plane points.

lines

In linear perspective, vertical lines stay vertical. See Figure 3. Scene points 1 and 2 make vertical line, and their picture-plane points make vertical line.

In linear perspective, horizontal lines stay horizontal. See Figure 4. Scene points 3 and 4 make horizontal line, and their picture-plane points make horizontal line.

The ground is plane and meets wall in horizontal line in scene and picture-plane. Ground meets sky in horizontal horizon line in scene and picture-plane.

horizon

Horizon height depends on eye height. Observer high above ground sees large ground amount and low horizon. Observer close to ground sees small ground amount and high horizon.

Observer attention typically moves along eye-level line.

line convergence

In linear perspective, non-vertical and non-right-left parallel lines converge and intersect at vanishing point. See Figure 5. Scene points 5/6 and 7/8 make two parallel lines, and their picture-plane points form two lines that converge toward a horizon point.

For parallel lines in horizontal plane, vanishing point is on horizon. For parallel lines in plane that rises as it goes farther from observer, vanishing point is above horizon. For parallel lines in plane that goes lower as it goes farther from observer, vanishing point is below horizon.

history

In Early Renaissance, Europeans studied al-Hazen's book [al-Haytham, 1010] about perspective and began to paint using linear perspective.