Depth perception

Space perception is the kinesthetic, auditory and visual experience and construction of space.

• 2.1 linear perspective
• 2.2 Relative Size
• 2.3 concealment - backdrop effect
• 2.4 shadow
• 2.5 Aerial perspective
• 2.6 Relative height
• 2.7 motion parallax

Binocular space perception

Similar to a camera creates the eye lens, a two-dimensional image of the environment on the retina. Nevertheless, a perception of space, so the seeing of spatial depth, possible. It is based on two principles: first, the distance of an object from the eyes is perceived to another is via the knowledge of the world and the objects they contain an interpretation of spatial depth.

Parallax

Humans and many animals have two eyes next to each other, which at the same time, the same point can be viewed in space and stereoscopic vision is possible. Due to the small lateral distance from the image of the two eyes is seen from a slightly different perspective, whereby lateral displacements (so-called lateral disparity ) between different points arising in the room. Up to a distance of about 10 meters this parallax can be interpreted by the brain as spatial depth information.

Accommodation

To see a point in space sharp, the curvature of the eye lens is varied (accommodation). By the time you learn what distance with which degree of curvature is related, so also vice versa from the change in lens curvature to draw conclusions about the spatial depth is possible. Here the distance is limited to about 10m.

Convergence

For viewing near objects, the eyes are turned from the nasal located eye muscles inward, while the eyes are parallel when viewing distant objects. Up to a distance of about 3 meters, the brain can extract information about the distance from the convergence of the visual axes.

Monocular perception of space

If a stereoscopic viewing is not possible or considered to an image such as a photograph or a painting, the spatial mapping must be reconstructed from the imaged objects. Conversely, the monocular cues used by painters, etc., to achieve a three-dimensional effect.

Linear perspective

Everyone knows the example of railroad tracks or a road that seems to unite to a point on the horizon. This effect of converging lines is characteristic of all straight edges and boundaries of bodies that are spatially parallel. We know that they are parallel, and are not tempted indeed to assume that they unite on the horizon - instead, we read their image than that of a spatial situation.

During the Renaissance, the geometric method of linear perspective experienced a high bloom and brought a wealth of painted trompe l' oeil forth. In the Baroque era, this law has also been used to produce stunning architectural effects in the smallest space, as masterfully Bernini in the forecourt of St. Peter's Basilica in Rome took place and downright virtuosic in the small staircase that leads into the more private apartments of the Pope, the famous Scala Regia right hand side of the main facade of St. Peter's.

Examples: On both images, the reality in parallel edges of road and shadow running on the photo to each other and are interpreted as a deep impression. From lack of experience, it also comes to misinterpretation, as solar radiation.

Relative size

Is us the size of an object is known, we can see from its relative size (how big it is on the retinal image ), to estimate its distance. We can see several identical objects in different relative sizes, so "read" this as we differ far away and not as different sized specimens that are at the same distance.

Masking - scenery effect

Due to the nature of our perceptual apparatus, involuntarily to fill in the missing pieces of the known forms in the spirit, we suspect in the case, in which a mold is obscuring another, one behind the other and did not come up with the idea that the only partially visible form is missing a piece. This principle we owe, among other things, the majestic effect of successive mountain ranges or the enormous spatial effect of the multi-wing Gothic cathedrals, the pillar and arch forests of the Alhambra in Granada, or even the cathedral -like effect of large beech forests.

In the theater, this effect is used together with the principle of size constancy to simulate spacious hall escapes in the limited space of the stage house. The more overlap can be seen from forms and the more layers we can see, the stronger is our impression of space.

Example: An example of consecutively arranged mountain shows the upper photograph.

Shadow

For more information about the three-dimensionality of bodies and spaces, we refer to the shadows they cast. From the light we see from the volume and surface quality, but also the dominant light direction and quality of light. Here, our brain in doubt presupposes that the light comes from above (so-called " light - from - above heuristic ), preferably from top left (at least in cultures that write from left to right and read). Way can we see whether it is convex or concave shapes are like the boundaries and transitions designed in between, etc. Accordingly, the shaded representation of the body increases their level of recognition. Proprietary shadow ( darker because light side) of a body gives him this volume and expansion, while the drop shadow (ie, the shadow which the body raises its surroundings ) defines its spatial relation to other areas and bodies - thereby also the principle of concealment (see above) there is the added effect.

Example: Examples and possible misinterpretations can be found in the article picture puzzle.

Aerial perspective

( See also: color perspective )

Objects far in the distance appear blurred, brighter and bluer. This distance information is thanks to the fact that we live in a turbid medium - the air that surrounds us. In the atmosphere of both the actual turbid air molecules as well as water vapor and suspended particles such as soot, smoke, sand or the sunlight and the light that is reflected from the objects.

This turbidity causes reduce the contrasts in the distance, black will change from black, white is no longer white, the colors lose their saturation point and on sunny days, an increasing proportion of blue, the further away their position by the viewer 's. This effect can be very well seen on days on which there is strong haze.

In contrast, eighth once on the lighting effect of the recordings of the astronauts on the moon or the images that were transferred from the Space Shuttle: No matter how small haze of the sky black; the lunar horizon and equal to about the little blue ball of our home planet seem close enough to touch.

Example: In the foreground in the photo above, the color of the trees is dark green. With increasing distance it brightens and moves into bluish. The distant mountains are only a little darker than the sky.

Relative height

Objects that are located in the two-dimensional image close to the horizon line are further away than interpreted as objects on it or be seen below. This heuristic is based, inter alia, the Moon illusion.

Motion parallax

We move through a scene ( eg in the car ), draw near objects more quickly on the eye over, than more distant. This is also called motion parallax.

Acoustic perception of space

Interiors can also be experienced acoustically; each has its specific acoustic signature space. Experienced listeners know, for example, even with closed eyes, whether they are in the Hall of the Musikverein in Vienna, in a warehouse ( Nachhall! ), or in the abbey church of Le Thoronet. Due to the 360 ° reception of the ears is the acoustic impression of space, unlike the visual, holistic.

Despite physical and acoustic sciences (eg for the construction of concert halls ) the neurobiological study acoustic perception of space is still in its infancy.

In bats, the perception of space is almost entirely acoustic, and even blind people can learn to use the light reflected from objects and walls of noise self-generated clicks for space perception.