SUMMARY OF JAMES J. GIBBSON'S THIRTEEN VARIETIES OF PERSPECTIVE AS ABSTRACTED FROM THE PERCEPTION OF THE VISUAL WORLD

1. TEXTS PERSPECTIVE:

This is the gradual increase in the density of the texture .of a surface as it recedes in the distance.

2. SIZE PERSPECTIVE:

As objects get farther away, they decrease in size (Apparently not recognized by the Italian painters in the twelfth century as applying to humans.)

3. LINEAR PERSPECTIVE:

Possibly the most commanly known form of perspective in the Western, worlds Renaissance art is the best known for its incorporation of the so-called laws of perspective Parallel lines like railroad tracks or highways that join at a single vanishing point at the horizon illustrate this form of perspective.

PERSPECTIVES OF PARALLAX


4. BINOCULAR PERSPECTIVE:

Binocular perspective operates very much out of awareness. It is sensed because, owing to the separation of the eyes, each [eye] projects a different image. The difference is much more apparent at close distances than at great distances. Closing and opening one eye and then the other makes the differences in the images apparent.

5. MOTION PERSPECTIVE:

As one moves forward in space, the closer one approaches a stationary object, the faster it appears to move. Likewise, objects moving at uniform speeds appear to be moving more slowly as distance increases.

PERSPECTIVES INDEPENDENT OF THE POSITION OR MOTION OF THE OBSERVER

6. AERIAL PERSPECTIVE :

Western ranchers used to have fun at the expense of dudes unfamiliar with regional differences in "aerial perspective." Untold numbers of these innocents would awaken refreshed and stimulated, look out the window and, seeing what looked like a nearby hill, announce that it was such a nice clear morning that they were going out for a walk to the hill and back before breakfast. Some were dissuaded. Others took off only to discover that the hill was little closer at the end of the half hour's walk than when they started. The "hill" proved to be a mountain anywhere from three to seven miles away and was seen in reduced scale because of an unfamiliar form of aerial perspective. The extreme clarity of the dry, high-altitude air altered the aerial perspective, giving the impression that everything was miles closer than it really was. From this we gather that aerial perspective is derived from the increased haziness and changes in color due to the intervening atmosphere. It is an indicator of distance, but not as reliable as some of the other forms of perspective.

7. THE PERSPECTIVE OF BLUR:

Photographers and painters are more likely than laymen to be aware of the perspective of blur. This form of visual space perception is evident when focusing on an object held out in front of the face, so that the background is blurred. Objects in a visual plane other than the one on which the eyes are focused will be seen less distinctly.

8. RELATIVE UPWARD LOCATION IN THE VISUAL FIELD:

On the deck of a ship or on the plains of Kansas and eastern Colorado, the horizon is seen as a line at about eye level. The surface of the globe climbs, as it were, from one's feet to eye level. The further from the ground one is, the more pronounced this effect. In the context of everyday experience, one looks down at objects that are close and up at objects that are far away.

9. SHIFT IN TEXTURE OR LINEAR SPACING:

A valley seen over the edge of a cliff is perceived as more distant because of the break or rapid increase in texture density. Although several years have passed since I first saw a certain Swiss valley, I can recall clearly the bizarre sensations it produced. Standing on a grassy ledge, I looked down 1500 feet at the streets and houses of a village. Blades of grass were sharply etched in the visual field, while each blade was the width of one of the small houses.

10. SHIFT IN THE AMOUNT OF DOUBLE IMAGERY:

If one looks at a distant point, everything between the viewer and the point will be seen as double. The closer to the viewer, the greater the doubling; the more distant the point, the less the doubling. The gradient in the shift is a clue to distance; a steep gradient is read as close, a gradual gradient as far.

11. SHIFT IN THE RATE OF MOTION:

One of the most dependable and consistent ways of sensing depth is the differential movement of objects in the visual field. Those objects which are close move much more than distant objects. They also move more quickly, as noticed in point #5. If two objects are seen as overlapping and they do not shift positions relative to each other when the viewer changes positions, they are either on the on the same plane or so far away that the shift is not perceived. Television audiences have become accustomed to perspective of this type because it is so pronounced whenever the camera moves through space in a manner similar to the moving viewer.

12. COMPLETENESS OR CONTINUITY OF OUTLINE:

One feature depth perception that has been exploited during wartime is continuity of outline. Camouflage is deceptive because it breaks the continuity. Even if there is no texture difference, no shift in the double imagery, and no shift in the rate of motion, the manner in which one object obscures (eclipses) another determines whether one is seen behind the other or not. If, for example, the outline of the nearest object is unbroken and that of the obscured objects is broken in the process of being eclipsed this fact will cause one object to appear behind the other.

13. TRANSITIONS BETWEEN LIGHT AND SHADE:

Just as an abrupt shift or change in the visual field will signal a cliff or an edge, so will an abrupt shift in brightness be interpreted as an edge. Gradual transitions in brightness are the principal means of perceiving modeling or roundness.