Linear Perspective - Linear perspective is a mathematical system for creating apparent depth and volume on a surface. Linear perspective has several aspects: (1) forms diminish in scale as they recede into the distance; (2) the point at which all forms completely disappear (are too small to see) is called a vanishing point; (3) in basic linear perspective (one-point and two-point perspective), the vanishing points are positioned at eye level, referred to as the horizon line; and (4) a fixed viewing point is required.
One-point perspective requires a single vanishing point on the horizon line to which all lines receding into space converge. If a cube is depicted, the viewer will face a flat plane of the cube. Two-point perspective requires two vanishing points on the horizon line. If a cube is depicted, the viewer will face an edge of the cube. Three-point perspective requires three vanishing points - usually two of the vanishing points are on the horizon line and a third is above or below the horizon line.
Atmospheric Perspective - Atmospheric perspective is a visual phenomenon in which the density of the atmosphere progressively increases through space, creating a 'haze.' Shapes become more ambiguous, colors become less saturated, and overall brightness can increase or decrease depending on the time of day.
* Alternate terms: aerial perspective
The Devil's Den on Cascade Creek
Overlap - Overlap is the placement of one shape in front of another to create the illusion of depth.
Shadows/Shading - Shadows/Shading is a depth cue that combines two elements. The first element is shadows which refers to the use of a cast shadow or shadows within an image. The second element is shading which refers to the use of a range of brightness to create plasticity.
* Alternate term: Chiaroscuro
An image without shadows or shading.
The result is a sense of volume and form. There is a sense of which parts of the spheres are closer to the viewer and which parts are further from the viewer.
With the addition of shadows, the spheres are not placed on a surface and it is apparent that the right-most sphere is actually closer to the viewer and floating above the ground plane.
The Fourth Tableau of Das Rheingold
A Bar at the Folies-Bergeres
1881-82, oil on canvas
(shading, minimal shadows)
c. 1658-60, oil on canvas
(shadows and shading)
Relative Size Relationship - Relative size reveals depth through what the mind translates as closer and further from a viewer. If an image contains two automobiles of the same model and one is larger than the other, the larger automobile will be perceived as closer to the viewer. The is related to how linear perspective works, but relative size does not require the other aspects of linear perspective such as a vanishing point.
The figure to the left is perceived as closer than the figure to the right.
A Sunday Afternoon on the Island of La Grande Jatte
1884-86, oil on canvas
(relative size of many figures)
Known Size or Scale - Known size or scale reveals depth through associations of figures and shapes that have an intrinsic size. A viewer knows that a house is larger than a mosquito so that if the two were approximately the same scale in an image, the house would be perceived as further away.
Even though the two figures are approximately the same size,
the assumption is made that the duck is closer to the viewer than the elephant
(as opposed to a giant duck or a miniature elephant).
The Great Wave Off Kanagawa
1823-29, color wookcut
(known size of a wave and the mountain)
Kinetic Depth (motion parallax) - Kinetic depth (or motion parallax) is a depth cue that is based on movement. As objects move through the field of vision, objects that are closer to the viewer move further across the field. In order to move further, closer objects also move faster.
Before playing the movie, try to determine which trees are closest to
the viewer and which are farthest away. Then play the movie.
Retinal disparity - Retinal disparity, sometimes called binocular disparity, is part of the process in visual perception that generates the depth and dimensionality. In the sequence of perception, this would occur at the surface/object stage. Specifically, retinal disparity is the space between the eyes that allows binocular vision to create depth perception.
The diagram indicates a left and right eye. Both eyes converge on a box but due to retinal disparity, the angle of viewing is slightly different for each eye. The brain combines the two images to create the perception of a three-dimensional object.