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 Depth perception is the ability to perceive distance to objects in the world using the visual system and visual perception. It is a major factor in perceiving the world in three dimensions. Depth perception happens primarily due to stereopsis and accommodation of the eye. Depth sensation is the corresponding term for non-human animals, since although it is known that they can sense the distance of an object, it is not known whether they perceive it in the same way that humans do.[1] Depth perception arises from a variety of depth cues. These are typically classified into binocular cues and monocular cues. Binocular cues are based on the receipt of sensory information in three dimensions from both eyes and monocular cues can be observed with just one eye.[2][3] Binocular cues include retinal disparity, which exploits parallax and vergence. Stereopsis is made possible with binocular vision. Monocular cues include relative size (distant objects subtend smaller visual angles than near objects), texture gradient, occlusion, linear perspective, contrast differences, and motion parallax.[4] Monocular cuesMonocular cues provide depth information when viewing a scene with one eye. Motion parallax When an observer moves, the apparent relative motion of several stationary objects against a background gives hints about their relative distance. If information about the direction and velocity of movement is known, motion parallax can provide absolute depth information.[5] This effect can be seen clearly when driving in a car. Nearby things pass quickly, while far off objects appear stationary. Some animals that lack binocular vision due to their eyes having little common field-of-view employ motion parallax more explicitly than humans for depth cueing (for example, some types of birds, which bob their heads to achieve motion parallax, and squirrels, which move in lines orthogonal to an object of interest to do the same[6]).[note 1] Depth from motion When an object moves toward the observer, the retinal projection of an object expands over a period of time, which leads to the perception of movement in a line toward the observer. Another name for this phenomenon is depth from optical expansion.[7] The dynamic stimulus change enables the observer not only to see the object as moving, but to perceive the distance of the moving object. Thus, in this context, the changing size serves as a distance cue.[8] A related phenomenon is the visual system's capacity to calculate time-to-contact (TTC) of an approaching object from the rate of optical expansion – a useful ability in contexts ranging from driving a car to playing a ball game. However, calculation of TTC is, strictly speaking, perception of velocity rather than depth. Kinetic depth effect If a stationary rigid figure (for example, a wire cube) is placed in front of a point source of light so that its shadow falls on a translucent screen, an observer on the other side of the screen will see a two-dimensional pattern of lines. But if the cube rotates, the visual system will extract the necessary information for perception of the third dimension from the movements of the lines, and a cube is seen. This is an example of the kinetic depth effect.[9] The effect also occurs when the rotating object is solid (rather than an outline figure), provided that the projected shadow consists of lines which have definite corners or end points, and that these lines change in both length and orientation during the rotation.[10] Perspective The property of parallel lines converging in the distance, at infinity, allows us to reconstruct the relative distance of two parts of an object, or of landscape features. An example would be standing on a straight road, looking down the road, and noticing the road narrows as it goes off in the distance. Visual perception of perspective in real space, for instance in rooms, in settlements and in nature, is a result of several optical impressions and the interpretation by the visual system. The angle of vision is important for the apparent size. A nearby object is imaged on a larger area on the retina, the same object or an object of the same size further away on a smaller area.[11] The perception of perspective is possible when looking with one eye only, but stereoscopic vision enhances the impression of the spatial. Regardless of whether the light rays entering the eye come from a three-dimensional space or from a two-dimensional image, they hit the inside of the eye on the retina as a surface. What a person sees, is based on the reconstruction by their visual system, in which one and the same image on the retina can be interpreted both two-dimensionally and three-dimensionally. If a three-dimensional interpretation has been recognised, it receives preference and determines the perception.[12]
In spatial vision, the horizontal line of sight can play a role. In the picture taken from the window of a house, the horizontal line of sight is at the level of the second floor (yellow line). Below this line, the further away objects are, the higher up in the visual field they appear. Above the horizontal line of sight, objects that are further away appear lower than those that are closer. To represent spatial impressions in graphical perspective, one can use a vanishing point.[13] When looking at long geographical distances, perspective effects also partially result by the angle of vision, but not only by this. In picture 5 of the series, in the background is Mont Blanc, the highest mountain in the Alps. It appears lower than the mountain in front in the center of the picture. Measurements and calculations can be used to determine the proportion of the curvature of Earth in the subjectively perceived proportions. Relative size If two objects are known to be the same size (for example, two trees) but their absolute size is unknown, relative size cues can provide information about the relative depth of the two objects. If one subtends a larger visual angle on the retina than the other, the object which subtends the larger visual angle appears closer. Familiar size Since the visual angle of an object projected onto the retina decreases with distance, this information can be combined with previous knowledge of the object's size to determine the absolute depth of the object. For example, people are generally familiar with the size of an average automobile. This prior knowledge can be combined with information about the angle it subtends on the retina to determine the absolute depth of an automobile in a scene. Absolute size Even if the actual size of the object is unknown and there is only one object visible, a smaller object seems further away than a large object that is presented at the same location.[14] Aerial perspective Due to light scattering by the atmosphere, objects that are a great distance away have lower luminance contrast and lower color saturation. Due to this, images seem hazy the farther they are away from a person's point of view. In computer graphics, this is often called "distance fog". The foreground has high contrast; the background has low contrast. Objects differing only in their contrast with a background appear to be at different depths.[15] The color of distant objects are also shifted toward the blue end of the spectrum (for example, distant mountains). Some painters, notably Cézanne, employ "warm" pigments (red, yellow and orange) to bring features forward towards the viewer, and "cool" ones (blue, violet, and blue-green) to indicate the part of a form that curves away from the picture plane. Accommodation This is an oculomotor cue for depth perception. When humans try to focus on distant objects, the ciliary muscles stretch the eye lens, making it thinner, and hence changing the focal length. The kinesthetic sensations of the contracting and relaxing ciliary muscles (intraocular muscles) is sent to the visual cortex where it is used for interpreting distance and depth. Accommodation is only effective for distances greater than 2 meters. Occultation Occultation (also referred to as interposition) happens when near surfaces overlap far surfaces.[16] If one object partially blocks the view of another object, humans perceive it as closer. However, this information only allows the observer to make a "ranking" of relative nearness. The presence of monocular ambient occlusions consist of the object's texture and geometry. These phenomena are able to reduce the depth perception latency both in natural and artificial stimuli.[17][18] Curvilinear perspective At the outer extremes of the visual field, parallel lines become curved, as in a photo taken through a fisheye lens. This effect, although it is usually eliminated from both art and photos by the cropping or framing of a picture, greatly enhances the viewer's sense of being positioned within a real, three-dimensional space. (Classical perspective has no use for this so-called "distortion", although in fact the "distortions" strictly obey optical laws and provide perfectly valid visual information, just as classical perspective does for the part of the field of vision that falls within its frame.) Texture gradient Fine details on nearby objects can be seen clearly, whereas such details are not visible on faraway objects. Texture gradients are grains of an item. For example, on a long gravel road, the gravel near the observer can be clearly seen of shape, size and colour. In the distance, the road's texture cannot be clearly differentiated. Lighting and shading The way that light falls on an object and reflects off its surfaces, and the shadows that are cast by objects provide an effective cue for the brain to determine the shape of objects and their position in space.[19] Defocus blur Selective image blurring is very commonly used in photographic and video for establishing the impression of depth. This can act as a monocular cue even when all other cues are removed. It may contribute to the depth perception in natural retinal images, because the depth of focus of the human eye is limited. In addition, there are several depth estimation algorithms based on defocus and blurring.[20] Some jumping spiders are known to use image defocus to judge depth.[21] Elevation When an object is visible relative to the horizon, humans tend to perceive objects which are closer to the horizon as being farther away from them, and objects which are farther from the horizon as being closer to them.[22] In addition, if an object moves from a position close the horizon to a position higher or lower than the horizon, it will appear to move closer to the viewer. Binocular cuesBinocular cues provide depth information when viewing a scene with both eyes. Stereopsis, or retinal (binocular) disparity, or binocular parallax Animals that have their eyes placed frontally can also use information derived from the different projection of objects onto each retina to judge depth. By using two images of the same scene obtained from slightly different angles, it is possible to triangulate the distance to an object with a high degree of accuracy. Each eye views a slightly different angle of an object seen by the left and right eyes. This happens because of the horizontal separation parallax of the eyes. If an object is far away, the disparity of that image falling on both retinas will be small. If the object is close or near, the disparity will be large. It is stereopsis that tricks people into thinking they perceive depth when viewing Magic Eyes, Autostereograms, 3-D movies, and stereoscopic photos. Convergence This is a binocular oculomotor cue for distance and depth perception. Because of stereopsis, the two eyeballs focus on the same object; in doing so they converge. The convergence will stretch the extraocular muscles – the receptors for this are muscle spindles. As happens with the monocular accommodation cue, kinesthetic sensations from these extraocular muscles also help in distance and depth perception. The angle of convergence is smaller when the eye is fixating on objects which are far away. Convergence is effective for distances less than 10 meters.[23] Shadow stereopsis Antonio Medina Puerta demonstrated that retinal images with no parallax disparity but with different shadows are fused stereoscopically, imparting depth perception to the imaged scene. He named the phenomenon "shadow stereopsis". Shadows are therefore an important, stereoscopic cue for depth perception.[24] Of these various cues, only convergence, accommodation and familiar size provide absolute distance information. All other cues are relative (as in, they can only be used to tell which objects are closer relative to others). Stereopsis is merely relative because a greater or lesser disparity for nearby objects could either mean that those objects differ more or less substantially in relative depth or that the foveated object is nearer or further away (the further away a scene is, the smaller is the retinal disparity indicating the same depth difference). Theories of evolutionThe law of Newton–Müller–GuddenIsaac Newton proposed that the optic nerve of humans and other primates has a specific architecture on its way from the eye to the brain. Nearly half of the fibres from the human retina project to the brain hemisphere on the same side as the eye from which they originate. That architecture is labelled hemi-decussation or ipsilateral (same sided) visual projections (IVP). In most other animals these nerve fibres cross to the opposite side of the brain. Bernhard von Gudden showed that the OC contains both crossed and uncrossed retinal fibers, and Ramon y Cajal[25] observed that the grade of hemidecussation differs between species.[26][25] Walls formalized a commonly accepted notion into the law of Newton–Müller–Gudden (NGM) saying: that the degree of optic fibre decussation in the optic chiasm is contrariwise related to the degree of frontal orientation of the optical axes of the eyes.[27][page needed] In other words, that the number of fibers that do not cross the midline is proportional to the size of the binocular visual field. However, an issue of the Newton–Müller–Gudden law is the considerable interspecific variation in IVP seen in non-mammalian species. That variation is unrelated to mode of life, taxonomic situation, and the overlap of visual fields.[28] Thus, the general hypothesis was for long that the arrangement of nerve fibres in the optic chiasm in primates and humans has developed primarily to create accurate depth perception, stereopsis, or explicitly that the eyes observe an object from somewhat dissimilar angles and that this difference in angle assists the brain to evaluate the distance. The eye-forelimb EF hypothesisThe EF hypothesis suggests that the need of accurate eye–hand control was key in the evolution of stereopsis. According to the EF hypothesis, stereopsis is evolutionary spinoff from a more vital process: that the construction of the optic chiasm and the position of eyes (the degree of lateral or frontal direction) is shaped by evolution to help the animal to coordinate the limbs (hands, claws, wings or fins).[29] The EF hypothesis postulates that it has selective value to have short neural pathways between areas of the brain that receive visual information about the hand and the motor nuclei that control the coordination of the hand. The essence of the EF hypothesis is that evolutionary transformation in OC will affect the length and thereby speed of these neural pathways.[30] Having the primate type of OC means that motor neurons controlling/executing let us say right hand movement, neurons receiving sensory e.g. tactile information about the right hand, and neurons obtaining visual information about the right hand, all will be situated in the same (left) brain hemisphere. The reverse is true for the left hand, the processing of visual, tactile information, and motor command – all of that takes place in the right hemisphere. Cats and arboreal (tree-climbing) marsupials have analogous arrangements (between 30 and 45% of IVP and forward directed eyes). The result will be that visual info of their forelimbs reaches the proper (executing) hemisphere. The evolution has resulted in small, and gradual fluctuations to the direction of the nerve pathways in the OC. This transformation can go in either direction.[29][31] Snakes, cyclostomes and other animals that lack extremities have relatively many IVP. Notably these animals have no limbs (hands, paws, fins or wings) to direct. Besides, left and right body parts of snakelike animals cannot move independently of each other. For example, if a snake coils clockwise, its left eye only sees the left body-part and in anti-clock-wise position the same eye will see just the right body-part. For that reason, it is functional for snakes to have some IVP in the OC (Naked). Cyclostome descendants (in other words most vertebrates) that due to evolution ceased to curl and, instead developed forelimbs would be favored by achieving completely crossed pathways as long as forelimbs were primarily occupied in lateral direction. Reptiles such as snakes that lost their limbs, would gain by recollect a cluster of uncrossed fibres in their evolution. That seems to have happened, providing further support for the EF hypothesis.[29][31] Mice' paws are usually busy only in the lateral visual fields. So, it is in accordance with the EF hypothesis that mice have laterally situated eyes and very few crossings in the OC. The list from the animal kingdom supporting the EF hypothesis is long (BBE). The EF hypothesis applies to essentially all vertebrates while the NGM law and stereopsis hypothesis largely applies just in mammals. Even some mammals display important exceptions, e.g. dolphins have only uncrossed pathways although they are predators.[31] It is a common suggestion that predatory animals generally have frontally-placed eyes since that permit them to evaluate the distance to prey, whereas preyed-upon animals have eyes in a lateral position, since that permit them to scan and detect the enemy in time. However, many predatory animals may also become prey, and several predators, for instance the crocodile, have laterally situated eyes and no IVP at all. That OC architecture will provide short nerve connections and optimal eye control of the crocodile's front foot.[31] Birds, usually have laterally situated eyes, in spite of that they manage to fly through e.g. a dense wood. In conclusion, the EF hypothesis does not reject a significant role of stereopsis, but proposes that primates' superb depth perception (stereopsis) evolved to be in service of the hand; that the particular architecture of the primate visual system largely evolved to establish rapid neural pathways between neurons involved in hand coordination, assisting the hand in gripping the correct branch[30]
Most open-plains herbivores, especially hoofed grazers, lack binocular vision because they have their eyes on the sides of the head, providing a panoramic, almost 360°, view of the horizon – enabling them to notice the approach of predators from almost any direction. However, most predators have both eyes looking forwards, allowing binocular depth perception and helping them to judge distances when they pounce or swoop down onto their prey. Animals that spend a lot of time in trees take advantage of binocular vision in order to accurately judge distances when rapidly moving from branch to branch. Matt Cartmill, a physical anthropologist & anatomist at Boston University, has criticized this theory, citing other arboreal species which lack binocular vision, such as squirrels and certain birds. Instead, he proposes a "Visual Predation Hypothesis," which argues that ancestral primates were insectivorous predators resembling tarsiers, subject to the same selection pressure for frontal vision as other predatory species. He also uses this hypothesis to account for the specialization of primate hands, which he suggests became adapted for grasping prey, somewhat like the way raptors employ their talons. In art
Photographs capturing perspective are two-dimensional images that often illustrate the illusion of depth. Photography utilizes size, environmental context, lighting, textural gradience, and other effects to capture the illusion of depth.[32] Stereoscopes and Viewmasters, as well as 3D films, employ binocular vision by forcing the viewer to see two images created from slightly different positions (points of view). Charles Wheatstone was the first to discuss depth perception being a cue of binocular disparity. He invented the stereoscope, which is an instrument with two eyepieces that displays two photographs of the same location/scene taken at relatively different angles. When observed, separately by each eye, the pairs of images induced a clear sense of depth.[33] By contrast, a telephoto lens—used in televised sports, for example, to zero in on members of a stadium audience—has the opposite effect. The viewer sees the size and detail of the scene as if it were close enough to touch, but the camera's perspective is still derived from its actual position a hundred meters away, so background faces and objects appear about the same size as those in the foreground. Trained artists are keenly aware of the various methods for indicating spatial depth (color shading, distance fog, perspective and relative size), and take advantage of them to make their works appear "real". The viewer feels it would be possible to reach in and grab the nose of a Rembrandt portrait or an apple in a Cézanne still life—or step inside a landscape and walk around among its trees and rocks. Cubism was based on the idea of incorporating multiple points of view in a painted image, as if to simulate the visual experience of being physically in the presence of the subject, and seeing it from different angles. The radical experiments of Georges Braque, Pablo Picasso, Jean Metzinger's Nu à la cheminée,[34] Albert Gleizes's La Femme aux Phlox,[35][36] or Robert Delaunay's views of the Eiffel Tower,[37][38] employ the explosive angularity of Cubism to exaggerate the traditional illusion of three-dimensional space. The subtle use of multiple points of view can be found in the pioneering late work of Cézanne, which both anticipated and inspired the first actual Cubists. Cézanne's landscapes and still lives powerfully suggest the artist's own highly developed depth perception. At the same time, like the other Post-Impressionists, Cézanne had learned from Japanese art the significance of respecting the flat (two-dimensional) rectangle of the picture itself; Hokusai and Hiroshige ignored or even reversed linear perspective and thereby remind the viewer that a picture can only be "true" when it acknowledges the truth of its own flat surface. By contrast, European "academic" painting was devoted to a sort of Big Lie that the surface of the canvas is only an enchanted doorway to a "real" scene unfolding beyond, and that the artist's main task is to distract the viewer from any disenchanting awareness of the presence of the painted canvas. Cubism, and indeed most of modern art is an attempt to confront, if not resolve, the paradox of suggesting spatial depth on a flat surface, and explore that inherent contradiction through innovative ways of seeing, as well as new methods of drawing and painting. In robotics and computer visionIn robotics and computer vision, depth perception is often achieved using sensors such as RGBD cameras.[39] See also
References
Notes
Bibliography
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Page 23D television (3DTV) is television that conveys depth perception to the viewer by employing techniques such as stereoscopic display, multi-view display, 2D-plus-depth, or any other form of 3D display. Most modern 3D television sets use an active shutter 3D system or a polarized 3D system, and some are autostereoscopic without the need of glasses. As of 2017, most 3D TV sets and services are no longer available from manufacturers.[1] HistoryThe stereoscope was first invented by Sir Charles Wheatstone in 1838.[2][3] It showed that when two pictures are viewed stereoscopically, they are combined by the brain to produce 3D depth perception. The stereoscope was improved by Louis Jules Duboscq, and a famous picture of Queen Victoria was displayed at The Great Exhibition in 1851. In 1855 the Kinematoscope was invented. In the late 1890s, the British film pioneer William Friese-Greene filed a patent for a 3D movie process. On 10 June 1915, former Edison Studios chief director Edwin S. Porter and William E. Waddell presented tests in red-green anaglyph to an audience at the Astor Theater in New York City and in 1922 the first public 3D movie The Power of Love was displayed. Stereoscopic 3D television was demonstrated for the first time on 10 August 1928, by John Logie Baird in his company's premises at 133 Long Acre, London.[4] Baird pioneered a variety of 3D television systems using electro-mechanical and cathode-ray tube techniques. The first 3D TV was produced in 1935, and stereoscopic 3D still cameras for personal use had already become fairly common by the Second World War. Many 3D movies were produced for theatrical release in the US during the 1950s just when television started to become popular. The first such movie was Bwana Devil from United Artists that could be seen all across the US in 1952. One year later, in 1953, came the 3D movie House of Wax which also featured stereophonic sound. Alfred Hitchcock produced his film Dial M for Murder in 3D, but for the purpose of maximizing profits the movie was released in 2D because not all cinemas were able to display 3D films. In 1946 the Soviet Union also developed 3D films, with Robinzon Kruzo being its first full-length 3D movie.[5] People were excited to view the 3D movies, but were put off by their poor quality. Because of this, their popularity declined quickly. There was another attempt in the 1970s and 1980s to make 3D movies more mainstream with the releases of Friday the 13th Part III (1982) and Jaws 3-D (1983).[6] Matsushita Electric (now Panasonic) developed a 3D television that employed an active shutter 3D system in the late 1970s. They unveiled the television in 1981, while at the same time adapting the technology for use with the first stereoscopic video game, Sega's arcade game SubRoc-3D (1982).[7] 3D film showings became more popular throughout the 2000s, culminating in the success of 3D presentations of Avatar in December 2009 and January 2010.[8] Though 3D movies were generally well received by the public, 3D television did not become popular until after the CES 2010 trade show, when major manufacturers began selling a full lineup of 3D televisions, following the success of Avatar.[9][10] Shortly thereafter, consumer and professional 3D camcorders were released to the public by Sony and Panasonic.[11][12][13] These used two lenses, one for each eye. According to DisplaySearch, 3D television shipments totaled 41.45 million units in 2012, compared with 24.14 in 2011 and 2.26 in 2010.[14] In late 2013, the number of 3D TV viewers started to decline,[15][16][17][18][19] and in 2016, development of 3D TV is limited to a few premium models.[20] Production of 3D TVs ended in 2016.[21] TechnologiesThere are several techniques to produce and display 3D moving pictures. The following are some of the technical details and methodologies employed in some of the more notable 3D movie systems that have been developed. The future of 3D television is also emerging as time progresses. New technology like WindowWalls (wall-size displays) and Visible light communication are being implemented into 3D television as the demand for 3D TV increases. Scott Birnbaum, vice president of Samsung's LCD business, said that the demand for 3D TV would skyrocket in the next couple of years, fueled by televised sports (but this did not happen). One might be able to obtain information directly onto their television due to new technologies like the Visible Light Communication that allows for this to happen because the LED lights transmit information by flickering at high frequencies.[22] Displaying technologiesThe basic requirement is to display offset images that are filtered separately to the left and right eye. Two strategies have been used to accomplish this: have the viewer wear eyeglasses to filter the separately offset images to each eye, or have the light source split the images directionally into the viewer's eyes (no glasses required).[23] Common 3D display technology for projecting stereoscopic image pairs to the viewer include:
In a CEATEC 2011 exhibition, Hitachi released glasses-free 3D projection systems that use a set of 24 projectors, lenses, and translucent half mirrors to superimpose 3D images with a horizontal viewing angle of 60 degrees and a vertical viewing angle of 30 degrees. Besides Hitachi, Sony is also working on similar technologies.[24] Single-view displays project only one stereo pair at a time. Multi-view displays either use head tracking to change the view depending on the viewing angle, or simultaneous projection of multiple independent views of a scene for multiple viewers (automultiscopic). Such multiple views can be created on the fly using the 2D-plus-depth format. Various other display techniques have been described, such as holography, volumetric display, and the Pulfrich effect, which was used in Doctor Who Dimensions in Time, in 1993, by 3rd Rock From The Sun in 1997, and by the Discovery Channel's Shark Week in 2000. 3D glasses may reduce image brightness.[25] Producing technologiesStereoscopy is the most widely accepted method for capturing and delivering 3D video. It involves capturing stereo pairs in a two-view setup, with cameras mounted side by side and separated by the same distance as is between a person's pupils. If we imagine projecting an object point in a scene along the line-of-sight for each eye, in turn; to a flat background screen, we may describe the location of this point mathematically using simple algebra. In rectangular coordinates with the screen lying in the Y–Z plane, with the Z axis upward and the Y axis to the right, with the viewer centered along the X axis; we find that the screen coordinates are simply the sum of two terms. One accounting for perspective and the other for binocular shift. Perspective modifies the Z and Y coordinates of the object point, by a factor of D/(D–x), while binocular shift contributes an additional term (to the Y coordinate only) of s·x/(2·(D–x)), where D is the distance from the selected system origin to the viewer (right between the eyes), s is the eye separation (about 7 centimeters), and x is the true x coordinate of the object point. The binocular shift is positive for the left-eye-view and negative for the right-eye-view. For very distant object points, the eyes will be looking along essentially the same line of sight. For very near objects, the eyes may become excessively "cross-eyed". However, for scenes in the greater portion of the field of view, a realistic image is readily achieved by superposition of the left and right images (using the polarization method or synchronized shutter-lens method) provided the viewer is not too near the screen and the left and right images are correctly positioned on the screen. Digital technology has largely eliminated inaccurate superposition that was a common problem during the era of traditional stereoscopic films.[26][27] Multi-view capture uses arrays of many cameras to capture a 3D scene through multiple independent video streams. Plenoptic cameras, which capture the light field of a scene, can also be used to capture multiple views with a single main lens.[28] Depending on the camera setup, the resulting views can either be displayed on multi-view displays, or passed along for further image processing. After capture, stereo or multi-view image data can be processed to extract 2D plus depth information for each view, effectively creating a device-independent representation of the original 3D scene. These data can be used to aid inter-view image compression or to generate stereoscopic pairs for multiple different view angles and screen sizes. 2D plus depth processing can be used to recreate 3D scenes even from a single view and convert legacy film and video material to a 3D look, though a convincing effect is harder to achieve and the resulting image will likely look like a cardboard miniature. 3D productionProduction of events such as live sports broadcasts in 3D differs from the methods used for 2D broadcasting. A high technical standard must be maintained because any mismatch in color, alignment, or focus between two cameras may destroy the 3D effect or produce discomfort in the viewer. Zoom lenses for each camera of a stereo pair must track over their full range of focal lengths. Addition of graphical elements (such as a scoreboard, timers, or logos) to a 3D picture must place the synthesized elements at a suitable depth within the frame, so that viewers can comfortably view the added elements as well as the main picture. This requires more powerful computers to calculate the correct appearance of the graphical elements. For example, the line of scrimmage that appears as a projected yellow line on the field during an American football broadcast requires about one thousand times more processing power to produce in 3D compared to a 2D image. Since 3D images are effectively more immersive than 2D broadcasts, fewer fast cuts between camera angles are needed. 3D National Football League broadcasts cut between cameras about one-fifth as often as in 2D broadcasting. Rapid cuts between two different viewpoints can be uncomfortable for the viewer, so directors may lengthen the transition or provide images with intermediate depth between two extremes to "rest" the viewer's eyes. 3D images are most effective if the cameras are at a low angle of view, simulating presence of the viewer at the event; this can present problems with people or structures blocking the view of the event. While fewer camera locations are required, the overall number of cameras is similar to a 2D broadcast because each position needs two cameras. Other live sport events have additional factors that affect production; for example, an ice rink presents few cues for depth due to its uniform appearance.[29] TV setsThese TV sets were high-end and generally included Ethernet, USB player and recorder, Bluetooth and USB Wi-Fi. 3D-ready TV sets3D-ready TV sets are those that can operate in 3D mode (in addition to regular 2D mode) using one of several display technologies to recreate a stereoscopic image. These TV sets usually supported HDMI 1.4 and a minimum output refresh rate of 120 Hz; glasses may be sold separately. Philips was developing a 3D television set that would be available for the consumer market by about 2011 without the need for special glasses (autostereoscopy).[30] However it was canceled because of the slow adoption of customers going from 2D to 3D.[citation needed] In August 2010, Toshiba announced plans to bring a range of autostereoscopic TVs to market by the end of the year.[31] The Chinese manufacturer TCL Corporation has developed a 42-inch (110 cm) LCD 3D TV called the TD-42F, which is currently available in China. This model uses a lenticular system and does not require any special glasses (autostereoscopy). It currently[when?] sells for approximately $20,000.[32][33] Onida, LG, Samsung, Sony, and Philips intended to increase their 3D TV offering with plans to make 3D TV sales account for over 50% of their respective TV distribution offering in 2012. It was expected that the screens would use a mixture of technologies until there is standardization across the industry.[34] Samsung offers the LED 7000, LCD 750, PDP 7000 TV sets and the Blu-ray 6900.[35] Full 3D TV setsFull 3D TV sets included Samsung Full HD 3D (1920×1080p, 60 Hz) and Panasonic Full HD 3D (1920×1080p, 60 Hz).[36] A September 2011 Cnet review touted Toshiba's 55ZL2 as "the future of television". Because of the demanding nature of auto-stereoscopic 3D technology, the display features a 3840x2160 display; however, there was at the time no video content available at this resolution. That said, it utilizes a multi-core processor to provide excellent upscaling to the "4k2k" resolution. Using a directional lenticular lenslet filter, the display generates nine 3D views. This technology commonly creates dead spots, which Toshiba avoids by using an eye-tracking camera to adjust the image. The reviewers also note that the 3D resolution for a 1080p signal looks more like 720p and lacks parallax, which reduces immersion. [37] Standardization effortsThe entertainment industry was expected to adopt a common and compatible standard for 3D in home electronics. To present faster frame rate in high definition to avoid judder (non-smooth, linear motion), enhancing 3-D film, televisions and broadcasting, other unresolved standards are the type of 3D glasses (passive or active), including bandwidth considerations, subtitles, recording format, and a Blu-ray standard. With improvements in digital technology, in the late 2000s, 3D movies became more practical to produce and display, putting competitive pressure behind the creation of 3D television standards. There are several techniques for Stereoscopic Video Coding, and stereoscopic distribution formatting including anaglyph, quincunx, and 2D plus Delta. Serial digital interface is used to carry 3D TV signals within TV stations.[38][39] Content providers, such as Disney, DreamWorks, and other Hollywood studios, and technology developers, such as Philips, asked[when?] SMPTE for the development of a 3DTV standard in order to avoid a battle of formats and to guarantee consumers that they will be able to view the 3D content they purchase and to provide them with 3D home solutions for all pockets. In August 2008, SMPTE established the "3-D Home Display Formats Task Force" to define the parameters of a stereoscopic 3D mastering standard for content viewed on any fixed device in the home, no matter the delivery channel. It explored the standards that need to be set for 3D content distributed via broadcast, cable, satellite, packaged media, and the Internet to be played-out on televisions, computer screens and other tethered displays. After six months, the committee produced a report to define the issues and challenges, minimum standards, and evaluation criteria, which the Society said would serve as a working document for SMPTE 3D standards efforts to follow. A follow-on effort to draft a standard for 3D content formats was expected to take another 18 to 30 months.[citation needed] Production studios were developing an increasing number of 3D titles for the cinema and as many as a dozen companies were actively working on the core technology behind the product.[when?] Many had technologies available to demonstrate, but no clear road forward for a mainstream offering emerged. Under these circumstances, SMPTE's inaugural meeting was essentially a call for proposals for 3D television; more than 160 people from 80 companies signed up for this first meeting. Vendors that presented their respective technologies at the task force meeting included SENSIO Technologies,[40] Philips, Dynamic Digital Depth (DDD),[41] TDVision,[42] and Real D, all of which had 3D distribution technologies. There were many active 3D projects in SMPTE for both TV and filmmakers in the late 2000s. The SMPTE 35PM40 Working Group decided (without influence from the SMPTE Board or any other external influence) that the good progress being made on 3D standards within other SMPTE groups (including the IMF Interoperable Master Format) meant that its "overview" project would be best published as an Engineering Report. However, by 2011, the SMPTE board had "abandoned all further work on 3D television".[43] However, SMPTE was not the only 3D standards group. Other organizations such as the Consumer Electronics Association (CEA),[44] 3D@Home Consortium,[45] ITU and the Entertainment Technology Center (ETC),[46] at USC School of Cinematic Arts have created their own investigation groups and have already offered to collaborate to reach a common solution. The Digital TV Group (DTG), has committed to profiling a UK standard for 3DTV products and services. Other standard groups such as DVB, BDA, ARIB, ATSC, DVD Forum, IEC and others were involved in the process.[citation needed] MPEG has been researching multi-view, stereoscopic, and 2D plus depth 3D video coding since the mid-1990s;[47] the first result of this research is the Multiview Video Coding extension for MPEG-4 AVC that is currently undergoing standardization. MVC has been chosen by the Blu-ray disc association for 3D distribution. The format offers backwards compatibility with 2D Blu-ray players.[48] HDMI version 1.4, released in June 2009, defines a number of 3D transmission formats. The format "Frame Packing" (left and right image packed into one video frame with twice the normal bandwidth) is mandatory for HDMI 1.4 3D devices. All three resolutions (720p50, 720p60, and 1080p24) have to be supported by display devices, and at least one of those by playback devices. Other resolutions and formats are optional.[49] While HDMI 1.4 devices will be capable of transmitting 3D pictures in full 1080p, HDMI 1.3 does not include such support. As an out-of-spec solution for the bitrate problem, a 3D image may be displayed at a lower resolution, like interlaced or at standard definition. DVB 3D-TV standardDVB has established the DVB 3D-TV Specification. The following 3D-TV consumer configurations will be available to the public:[50]
For the two broadcast scenarios above, initial requirements are for Pay-TV broadcasters to deliver 3D-TV services over existing HD broadcasting infrastructures, and to use existing receivers (with firmware upgrade, as required) to deliver 3D content to 3D-TV sets, via an HDMI or equivalent connection, if needed. This is termed Frame Compatible. There are a range of Frame Compatible formats. They include the Side by Side (SbS) format, the Top and Bottom (TaB) format, and others. BroadcastsA diagram of the 3D TV scheme. 3D channels
In 2008, 3D programming was broadcast on Japanese satellite BS11 approximately four times per day.[51] Cablevision launched a 3D version of its MSG channel on 24 March 2010, which was a limited service that was only available only to Cablevision subscribers on channel 1300.[52][53] The channel was dedicated primarily to sports broadcasts, including MSG's 3D broadcast of a New York Rangers-New York Islanders game, limited coverage of the 2010 Masters Tournament, and (in cooperation with YES Network) a game between the New York Yankees and Seattle Mariners.[54] The first Australian program broadcast in high-definition 3D was Fox Sports coverage of the soccer game Australia-New Zealand on 24 May 2010.[55] Also in Australia, the Nine Network and Special Broadcasting Service brought the State of Origin (matches on 26 May, 16 June and 7 July 2010) (Nine) and FIFA World Cup (SBS) in 3D on Channel 40 respectively.[56] In early 2010, Discovery Communications, Imax, and Sony announced plans to launch a 3D TV channel in the US with a planned launch in early 2011. At the same time, a Russian company Platform HD and its partners – General Satellite and Samsung Electronics – announced about their 3D television project, which would be the first similar project in Russia. In Brazil Rede TV! became the first Terrestrial television to transmit 3D signal freely for all 3D enabled audience on 21 May.[57][58][59] Starting on 11 June 2010, ESPN launched a new channel, ESPN 3D, dedicated to 3D sports with up to 85 live events a year in 3D.[60] On 1 January 2010, the world's first 3D channel, SKY 3D, started broadcasting nationwide in South Korea by Korea Digital Satellite Broadcasting. The channel's slogan is "World No.1 3D Channel". This 24/7 channel uses the Side by Side technology at a resolution of 1920x1080i. 3D contents include education, animation, sport, documentary and performances.[61] A full 24-hour broadcast channel was announced at the 2010 Consumer Electronics show as a joint venture from IMAX, Sony, and the Discovery channel.[62] The intent was to launch the channel in the United States by year end 2010. However, this did not materialize in time. DirecTV and Panasonic launched 2 broadcast channels and 1 Video on demand channel with 3D content[63] in June 2010. DirecTV previewed a live demo of their 3D feed at the Consumer Electronics Show held 7–10 January 2010.[64] In Europe, British Sky Broadcasting (Sky) launched a limited 3D TV broadcast service on 3 April 2010. Transmitting from the Astra 2A satellite at 28.2° east, Sky 3D broadcast a selection of live English Premier League football matches to over 1000 British pubs and clubs equipped with a Sky+HD Digibox and 3D Ready TVs, and preview programmes provided for free to top-tier Sky HD subscribers with 3D TV equipment. This was later expanded to include a selection of films, sports, and entertainment programming launched to Sky subscribers on 1 October 2010.[65] On 28 September 2010, Virgin Media launched a 3D TV on Demand service.[66] Several other European pay-TV networks are also planning 3D TV channels and some have started test transmissions on other Astra satellites, including French pay-TV operator Canal+ which has announced its first 3D channel is to be launched in December 2010. Also the Spanish Canal+ has started the first broadcastings on 18 May 2010 and included 2010 FIFA World Cup matches in the new Canal+ 3D channel.[67] Satellite operator SES started a free-to-air 3D demonstration channel on the Astra satellite at 23.5° east on 4 May 2010 for the opening of the 2010 ANGA Cable international trade fair[68] using 3D programming supplied by 3D Ready TV manufacturer Samsung under an agreement between Astra and Samsung to co-promote 3D TV.[69] By November 2010, there were eight 3D channels broadcasting to Europe from three Astra satellite positions, including demonstrations provided by Astra, pay-TV from BSkyB, Canal+ and others, and the Dutch Brava3D cultural channel, which provides a mix of classical music, opera and ballet free-to-air across Europe from Astra 23.5°E.[70] In April 2011, HIGH TV (a 3D family entertainment channel) launched. Headquartered in NY with offices in Hong Kong and London, the channel broadcasts through eight satellites round the world, covering Europe, Asia, the Nordic region, Russia, South America, Africa, Middle East and North America. 3flow is a 3D channel that began broadcasting on Freebox in France on 1 April 2011. Made up entirely of native stereoscopic programming produced and owned by WildEarth and Sasashani (WildEarth's parent company). Initially the focus was mostly safari and has now widened to include underwater, extreme sports and other 3D content from around the world. WildEarth and Sasashani also distribute 3D series and shows through 3D Content Hub. On 1 January 2012, China's first 3D Test Channel launched on China Central Television and 5 other networks.[71] On 1 February 2012: The Extreme Sports Channel – the home of Extreme Sports launched in Italy on Sky Italia marking its international début in high definition (HD).[72] The channel's HD feed will be a simulcast of the standard definition feed launched in 1999, which now broadcasts to subscribers in 66 territories and in 12 languages across Europe, the Middle East and Africa (EMEA). The inaugural launch on Italy's Sky platform sees the channel's entrance into the HD market and from there it will begin rolling out to operators across the EMEA region. In February 2012 Telecable de Tricom, a major Dominican cable TV provider, announced the launch of the first 3D TV programming package in Latin America. As of 3 July 2012, the only 3D channels available are 3flow and HIGH TV 3D.[73] In July 2013 the BBC announced that it would be indefinitely suspending 3D programming due to a lack of uptake. Only half of the estimated 1.5 million households in the UK with a 3D-enabled television watched the 2012 summer's Olympics opening ceremony in 3D.[74] In 2013, in the US, ESPN 3D was shut down due to lack of demand, followed by Xfinity 3D and all DirecTV 3D programming in 2014. List of 3D TV channels
Standard HD channels have also broadcast in 3D. BBC HD occasionally broadcast high-profile events in 3D including the Wimbledon men's & ladies' singles finals and the opening and closing ceremonies of the 2012 Summer Olympics. However the BBC abandoned 3D broadcasting following the 2013 Wimbledon tennis championships.[76] 3D episodes and showsThere have been several notable examples in television where 3D episodes have been produced, typically as one-hour specials or special events. 1980sThe first-ever 3D broadcast in the UK was an episode of the weekly science magazine The Real World, made by Television South and screened in the UK in February 1982. The program included excerpts of test footage shot by Philips in the Netherlands. Red/green 3D glasses were given away free with copies of the TV Times listings magazine, but the 3D sections of the programme were shown in monochrome. The experiment was repeated nationally in December 1982, with red/blue glasses allowing color 3D to be shown for the first time. The program was repeated the following weekend followed by a rare screening of the Western Fort Ti starring George Montgomery and Joan Vohs. In 1985 Portugal's national TV channel RTP 1 broadcast the movie Creature from the Black Lagoon in anaglyph format. Red/cyan 3D glasses were sold with magazines.[77][78] 1990sIn November 1993, the BBC announced a one-off week of 3D programming filmed using the pioneering Pulfrich 3D technique. 3D glasses were sold in shops around the UK, a percentage of the sales going to the Children In Need charity. The week's programming concluded with a screening of the 3D Doctor Who special "Dimensions In Time" as well as specially shot segments of Noel's House Party and the annual Children In Need charity appeal. 3D television episodes were a brief fad on U.S. television during the May 1997 sweeps. The sitcom 3rd Rock from the Sun showed a two-part episode, "Nightmare On Dick Street", where several of the characters' dreams are shown in 3D. The episode cued its viewers to put on their 3D glasses (which used the Pulfrich effect) by including "3D on" and "3D off" icons in the corner of the screen as a way to alert them as to when the 3D sequences would start and finish. Customers were given free glasses courtesy of a joint venture between Little Caesars pizza and Barq's Root Beer. Also in May 1997, ABC had a special line-up of shows that showcased specific scenes in 3D. The shows included Home Improvement, Spin City, The Drew Carey Show, Ellen, Family Matters, Step by Step, Sabrina, The Teenage Witch, and America's Funniest Home Videos. Similar to 3rd Rock, an icon alerted viewers when to put on the 3D glasses. Customers were given free anaglyph glasses at Wendy's for the promotion. Nickelodeon had a special lineup of shows in 1997 that also showcased specific scenes in 3D promoted as Nogglevision; ChromaDepth was the technology of choice for Nickelodeon's 3D. 2000sRecent uses of 3D in television include the drama Medium and the comedy Chuck (Season 2, episode 12). Channel 4 in the UK ran a short season of 3D programming in November 2009 including Derren Brown and The Queen in 3D. Unlike previous British 3D TV experiments, the programmes were transmitted in ColorCode 3D.[79] In May 2006 Portugal's national TV channel RTP 1 broadcast several shows in anaglyph format ("Real 3D") for a week. Red/cyan 3D glasses were sold exclusively by a hypermarket chain.[77] 2010sOn 31 January 2010, BSKYB became the first broadcaster in the world to show a live sports event in 3D when Sky Sports screened a football match between Manchester United and Arsenal to a public audience in several selected pubs.[80] On 31 January 2010, the 52nd Grammy Awards featured a Michael Jackson Tribute Sequence in 3D, using anaglyph format. The very first stereoscopic indie live action comedy one-hour show called Safety Geeks : SVI : 3D specifically for 3DTV and 3D VOD was produced and released in March 2010 through Digital Dynamic Depth / Yabazam and their Yabazam website portal.[81] Safety Geeks:SVI is the comic adventures of an elite force of safety experts, the P.O.S.H. (Professional Occupational Safety Hazard) team. Obsessed with making the world safer, the CSI-like team investigates accidents to find out what went wrong and who is to blame. It won the Los Angeles 3D film Festival in 2010 as best pilot or series in 3D. In April 2010, the Masters Tournament was broadcast in live 3D on DirecTV, Comcast, and Cox. The Roland Garros tennis tournament in Paris, from 23 May to 6 June 2010, was filmed in 3D (center court only) and broadcast live via ADSL and fiber to Orange subscribers throughout France in a dedicated Orange TV channel.[82] Fox Sports broadcasts the first program in 3D in Australia when the Socceroos played The New Zealand All Whites at the MCG on 24 May 2010. The Nine Network broadcast the first Free-to-air 3D telecast when the Queensland Maroons faced the New South Wales Blues at ANZ Stadium on 26 May 2010. On 29 May 2010, Sky broadcasts Guinness Premiership Final in 3D in selected pubs and clubs.[83] 25 matches in the FIFA World Cup 2010 were broadcast in 3D. The Inauguration of Philippine President Noynoy Aquino on 30 June 2010 was the first presidential inauguration to telecast in live 3D by GMA Network. However, the telecast was only available in select places. The 2010 Coke Zero 400 was broadcast in 3D on 3 July on NASCAR.com and DirecTV along with Comcast, TWC, and Bright House cable systems. Astro broadcast the 2010 FIFA World Cup Final on 11 July 2010 in 3-D on their B.yond service. Satellite delivered Bell TV in Canada began to offer a full-time pay-TV, 3D channel to its subscribers on 27 July 2010. The 2010 PGA Championship was broadcast in 3D for four hours on 13 August 2010, from 3–7 pm EDT. The broadcast was available on DirecTV, Comcast, Time Warner Cable, Bright House Networks, Cox Communications, and Cablevision.[84] In September 2010, the Canadian Broadcasting Corporation's first 3D broadcast was a special about the Canadian monarch, Elizabeth II, and included 3-D film footage of the Queen's 1953 coronation as well as 3D video of her 2010 tour of Canada. This marks the first time the historical 3D images have been seen anywhere on television as well as the first broadcast of a Canadian produced 3D programme in Canada.[85] FioS and the NFL partnered to broadcast 2 September 2010, pre-season game between the New England Patriots and the New York Giants in 3D. The game was only broadcast in 3D in the northeast.[86] The 2010 AFL Grand Final, on 25 September 2010, was broadcast in 3D from the Seven Network. Rachael Ray aired a 3D Halloween Bash on 29 October 2010. The first Japanese television series in 3D, Tokyo Control, premiered on 19 January 2011.[87] In May 2011, 3net released the first docu-reality TV series entitled Bullproof filmed in native 3D made by Digital Revolution Studios. The 2011 3D Creative Arts Awards "Your World in 3D" was the first award show filmed in native 3D and televised on 3net 3D channel broadcast on DirectTV. The production was filmed at the Grauman's Chinese Theatre in Hollywood. On 16 July 2011 – The Parlotones (South African Rock Act) became the first band to broadcast a Live Rock Opera to Terrestrial CInema in 3D, a Live 3D feed to DIRECT TV in the US and Facebook pay per view. It was called "Dragonflies & Astronauts". The semi-finals, Bronze Final and Final matches of the 2011 Rugby World Cup will be broadcast in 3D. Singapore based Tiny Island Productions is currently producing Dream Defenders, which will be available in both autostereoscopic and stereoscopic 3D formats.[88] 3net, which acquired the series, describes it as the first stereoscopic children's series and will air on 25 September 2011.[89] In July 2011, the BBC announced that the grand final of Strictly Come Dancing in December 2011 will air in 3-D. The BBC broadcast the 2011 finals of the Wimbledon Lawn Tennis Championships in 3D.[90] In February 2012 Telecable de Tricom, a major Dominican cable TV provider, announced the launch of the first 3D TV programming package in Latin America. As of 10 August 2012 the only 3D channels available are Wildearth, 3 Flow 3D, and High TV 3D.[91] Avi Arad is currently developing a 3D Pac-Man TV show.[92] The Xbox Live broadcasts of the 2012 Miss Universe and Miss USA beauty pageants were available in RealD 3D. In 2013, in Brazil, NET HD pay-per-view broadcasts of the thirteenth season of Big Brother Brasil were available in 3D.[93][94] In July 2013, the BBC announced that they were putting 3D broadcasts on hold due to lack of audience interest, even from those who owned 3D TV displays.[95] As one of their final 3D broadcasts, 23 November 2013, the BBC aired a special 3D episode of Doctor Who in celebration of that show's fiftieth anniversary. That episode, The Day of the Doctor, was filmed and produced in 3D, and broadcast in 2D and 3D in the UK, with simultaneous showings in 3D in cinemas around the world. It has since been made available on 3D Blu-ray.[96] DeclineAs early as 2013, 3D televisions were being seen as a fad.[97][98] DirecTV had stopped broadcasting 3D programs in 2012, while ESPN stopped in 2013.[99] In the UK, Sky moved its content to on-demand, and the BBC ended airing 3D shows in 2013 due to "lack of public appetite".[100][101] Fewer and fewer 3D TVs were sold and soon TV manufacturers stopped making them. Vizio stopped production in 2014 and was followed by others.[102] In January 2017, the last two major television manufacturers still producing 3D televisions, Sony and LG, announced they would stop all 3D support.[99] World recordThe 2011 UEFA Champions League Final match between Manchester United and Barcelona was broadcast live in 3D format on a Ukrainian-produced EKTA screen in Gothenburg, Sweden. The screen made it to The Guinness Book of World Records as the world's biggest screen.[103][104] The live 3D broadcast was provided by the company Viasat.[105] Health effectsSome viewers have complained of headaches, seizures and eyestrain after watching 3D films.[106][107] There have been several warnings, especially for the elderly.[108] Motion sickness, in addition to other health concerns,[109] is more easily induced by 3D presentations. There are primarily two effects of 3D TV that are unnatural for the human vision: crosstalk between the eyes caused by imperfect image separation and the mismatch between convergence and accommodation caused by the difference between an object's perceived position in front of or behind the screen and the real origin of that light on the screen.[110] It is believed that approximately 12% of people are unable to properly see 3D images, owing to a variety of medical conditions.[111][112] According to another experiment, up to 30% of people have very weak stereoscopic vision preventing depth perception based on stereo disparity. This nullifies or greatly decreases immersion effects of digital stereo to them.[113] See also
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