Depth Perception and the Perception of Events

Abstract

Three fundamental questions are addressed: (1) What are the effective sources of optical information for perceiving spatial relationships and events? Complex natural environments provide a plethora of information potentially related to spatial layout. Psychophysical research investigates the efficacy and perceptual processing of these potential cues to depth and events. (2) How is this information combined by the perceptual system? Viewed in isolation, individual cues typically do not fully specify the environmental properties to which they relate. In general, the rules for projecting three‐dimensional layout onto the retina are unambiguously defined, whereas the inverse operation—from the image to the three‐dimensional projected scene—is not. (3) Do people perceive space and events accurately? Certainly, people act in the environment as if they represent its spatial relationships accurately; however, effective action can often be achieved without geometrically correct representations. From a pragmatic perspective, perceptual representations are accurate to the degree that they provide effective guidance for behavior. This issue is developed and discussed throughout the chapter.

Stereoscopic Depth Cues Outperform Monocular Ones on Autostereoscopic Display

“…When the size of an object is known to the observer the source of information becomes familiar and gives an anchor for estimating the distance. In natural viewing conditions the familiar size does not have such a great effect on perceived distance [22], but has a greater effect especially in conditions where there is lesser information provided by other cues [23]. When sizes of objects on the scene are not known, in order to make an estimation of distance, the scene must have several objects that can be assumed to have the same size.…”

“…Regarding the texture, the shape of each element must be known in order to define whether there has been compression due to slant. Besides the retinal size and foreshortening, a third way of retrieving information from texture cues is to evaluate texture density -the spatial distribution of the texture elements' centres in the image [23].…”

“…The depth cue works similarly for underwater environments and estimation of depth from transparency. Color as a depth cue has been studied also by [23].…”

“…Another limitation of the cue is that with great distances objects become indistinct. Depth estimation from aerial perspective requires knowledge of the reflectance value of the object, and of the attenuation coefficient of the atmosphere [23].…”

“…Vergence may not be very reliable cue for perceiving absolute depth but may be more important for ordinal-depth information [23]. The effective range of vergence is best for distances up to 2 m. However, it is usually combined with accommodation, and then the range is increased to be less than 3 m [26].…”