The Depth Perception Cue Employed in Old Fashioned Stereoscopes but Not in Plain Photographs Is:

Technique for creating or enhancing the illusion of depth in an image

Pocket stereoscope with original exam epitome. Used by military to examine stereoscopic pairs of aerial photographs.

View of Boston, c. 1860; an early stereoscopic card for viewing a scene from nature

Stereoscopic image of 787 Orange Street, Addison R. Tinsley firm, circa 1890s.

Stereoscopic epitome of 772 College Street (formerly Johnson Street) in Macon, Ga, circa 1870s.

Kaiserpanorama consists of a multi-station viewing appliance and sets of stereo slides. Patented by A. Fuhrmann effectually 1890.^[1]

A visitor of ladies looking at stereoscopic views, painting past Jacob Spoel, earlier 1868. An early depiction of people using a stereoscope.

Stereoscopy (as well called stereoscopics, or stereo imaging) is a technique for creating or enhancing the illusion of depth in an image by means of stereopsis for binocular vision.^[ii] The word stereoscopy derives from Greek στερεός (stereos) 'business firm, solid', and σκοπέω (skopeō) 'to look, to run across'.^{[3] [iv]} Whatsoever stereoscopic image is chosen a stereogram. Originally, stereogram referred to a pair of stereo images which could be viewed using a stereoscope.

Most stereoscopic methods present two offset images separately to the left and right eye of the viewer. These two-dimensional images are and then combined in the encephalon to requite the perception of 3D depth. This technique is distinguished from 3D displays that display an prototype in 3 full dimensions, allowing the observer to increase information near the three-dimensional objects being displayed by head and eye movements.

Background [edit]

Stereoscopy creates the illusion of iii-dimensional depth from given two-dimensional images.^[v] Human vision, including the perception of depth, is a complex process, which only begins with the acquisition of visual information taken in through the optics; much processing ensues within the brain, as it strives to make sense of the raw information. One of the functions that occur inside the encephalon as it interprets what the eyes encounter is assessing the relative distances of objects from the viewer, and the depth dimension of those objects. The cues that the encephalon uses to estimate relative distances and depth in a perceived scene include^[six]

• Stereopsis
• Accommodation of the heart
• Overlapping of one object by another
• Subtended visual bending of an object of known size
• Linear perspective (convergence of parallel edges)
• Vertical position (objects closer to the horizon in the scene tend to be perceived as farther away)
• Haze or contrast, saturation, and color, greater distance generally being associated with greater haze, desaturation, and a shift toward bluish
• Change in size of textured pattern detail

(All but the first two of the above cues exist in traditional two-dimensional images, such equally paintings, photographs, and television.)^[7]

Stereoscopy is the production of the illusion of depth in a photograph, movie, or other two-dimensional image by the presentation of a slightly unlike image to each eye, which adds the first of these cues (stereopsis). The two images are and so combined in the brain to give the perception of depth. Because all points in the image produced past stereoscopy focus at the same plane regardless of their depth in the original scene, the 2nd cue, focus, is not duplicated and therefore the illusion of depth is incomplete. There are besides mainly two effects of stereoscopy that are unnatural for human being vision: (1) the mismatch betwixt convergence and accommodation, caused by the difference between an object'due south perceived position in front of or behind the display or screen and the real origin of that light; and (ii) possible crosstalk between the optics, caused by imperfect image separation in some methods of stereoscopy.

Although the term "3D" is ubiquitously used, the presentation of dual 2d images is distinctly unlike from displaying an image in iii full dimensions. The virtually notable divergence is that, in the case of "3D" displays, the observer's head and heart motion practise not alter the data received about the three-dimensional objects beingness viewed. Holographic displays and volumetric display do not have this limitation. But as it is not possible to recreate a full 3-dimensional sound field with just two stereophonic speakers, it is an overstatement to call dual 2D images "3D". The accurate term "stereoscopic" is more cumbersome than the common misnomer "3D", which has been entrenched by many decades of unquestioned misuse. Although nearly stereoscopic displays do not authorize as existent 3D display, all real 3D displays are also stereoscopic displays because they meet the lower criteria also.

Most 3D displays apply this stereoscopic method to convey images. It was first invented by Sir Charles Wheatstone in 1838,^{[8] [9]} and improved by Sir David Brewster who made the first portable 3D viewing device.^[10]

Wheatstone mirror stereoscope

Brewster-type stereoscope, 1870

Wheatstone originally used his stereoscope (a rather beefy device)^[11] with drawings because photography was non nonetheless available, yet his original paper seems to foresee the development of a realistic imaging method:^[12]

For the purposes of illustration I have employed but outline figures, for had either shading or colouring been introduced it might be supposed that the effect was wholly or in office due to these circumstances, whereas by leaving them out of consideration no room is left to doubt that the unabridged issue of relief is attributable to the simultaneous perception of the 2 monocular projections, one on each retina. Only if it be required to obtain the most faithful resemblances of real objects, shadowing and colouring may properly be employed to raise the effects. Careful attending would enable an artist to draw and pigment the two component pictures, so every bit to nowadays to the mind of the observer, in the resultant perception, perfect identity with the object represented. Flowers, crystals, busts, vases, instruments of various kinds, &c., might thus be represented so as not to be distinguished past sight from the real objects themselves.^[8]

Stereoscopy is used in photogrammetry and also for entertainment through the production of stereograms. Stereoscopy is useful in viewing images rendered from big multi-dimensional data sets such as are produced by experimental information. Modernistic industrial 3-dimensional photography may use 3D scanners to notice and record three-dimensional data.^[13] The three-dimensional depth information tin exist reconstructed from 2 images using a reckoner by correlating the pixels in the left and correct images.^[xiv] Solving the Correspondence problem in the field of Computer Vision aims to create meaningful depth information from two images.

Visual requirements [edit]

Anatomically, in that location are 3 levels of binocular vision required to view stereo images:

1. Simultaneous perception
2. Fusion (binocular 'single' vision)
3. Stereopsis

These functions develop in early on babyhood. Some people who have strabismus disrupt the development of stereopsis, however orthoptics handling tin be used to improve binocular vision. A person's stereoacuity^[fifteen] determines the minimum image disparity they can perceive as depth. It is believed that approximately 12% of people are unable to properly come across 3D images, due to a variety of medical conditions.^{[xvi] [17]} According to another experiment up to xxx% of people have very weak stereoscopic vision preventing them from depth perception based on stereo disparity. This nullifies or greatly decreases immersion effects of stereo to them.^[18]

Saul Davis (act. 1860s–1870s), New Intermission Bridge, Niagara Falls, Canada, c. 1869, albumen print stereograph, Department of Paradigm Collections, National Gallery of Fine art Library, Washington, DC

Stereoscopic viewing may exist artificially created by the viewer's brain, every bit demonstrated with the Van Hare Effect, where the brain perceives stereo images even when the paired photographs are identical. This "imitation dimensionality" results from the adult stereoacuity in the brain, assuasive the viewer to fill in depth data even when few if any 3D cues are actually available in the paired images.

Side-by-side [edit]

Traditional stereoscopic photography consists of creating a 3D illusion starting from a pair of 2D images, a stereogram. The easiest way to enhance depth perception in the encephalon is to provide the eyes of the viewer with ii unlike images, representing two perspectives of the same object, with a small-scale deviation equal or near equal to the perspectives that both eyes naturally receive in binocular vision.

A stereoscopic pair of images (top) and a combined anaglyph that colors i perspective crimson and the other cyan.
3D cherry cyan glasses are recommended to view this image correctly.

Ii Passiflora caerulea flowers bundled equally a stereo image pair for viewing by the cantankerous-eyed viewing method (run into Freeviewing)

To avoid eyestrain and distortion, each of the two 2nd images should be presented to the viewer so that any object at space altitude is perceived by the heart equally being straight ahead, the viewer's eyes being neither crossed nor diverging. When the motion-picture show contains no object at infinite distance, such as a horizon or a cloud, the pictures should exist spaced correspondingly closer together.

The advantages of side-past-side viewers is the lack of diminution of effulgence, allowing the presentation of images at very high resolution and in full spectrum color, simplicity in creation, and little or no additional prototype processing is required. Under some circumstances, such as when a pair of images is presented for freeviewing, no device or additional optical equipment is needed.

The primary disadvantage of side-by-side viewers is that big image displays are not practical and resolution is limited by the lesser of the display medium or human heart. This is because as the dimensions of an image are increased, either the viewing apparatus or viewer themselves must move proportionately further away from it in guild to view it comfortably. Moving closer to an image in order to see more particular would but be possible with viewing equipment that adjusted to the divergence.

Printable cross eye viewer.

Freeviewing [edit]

Freeviewing is viewing a side-by-side paradigm pair without using a viewing device.^[two]

Two methods are bachelor to freeview:^{[fifteen] [19]}

• The parallel viewing method uses an epitome pair with the left-eye image on the left and the right-eye image on the right. The fused three-dimensional prototype appears larger and more distant than the two actual images, making it possible to convincingly simulate a life-size scene. The viewer attempts to wait through the images with the eyes substantially parallel, as if looking at the actual scene. This tin can be difficult with normal vision because eye focus and binocular convergence are habitually coordinated. One approach to decoupling the two functions is to view the image pair extremely shut upward with completely relaxed eyes, making no attempt to focus conspicuously only simply achieving comfortable stereoscopic fusion of the two blurry images by the "wait-through" approach, and just then exerting the effort to focus them more clearly, increasing the viewing altitude equally necessary. Regardless of the arroyo used or the image medium, for comfortable viewing and stereoscopic accurateness the size and spacing of the images should be such that the corresponding points of very distant objects in the scene are separated by the same distance as the viewer'due south eyes, only not more; the average interocular distance is about 63 mm. Viewing much more widely separated images is possible, just because the optics never diverge in normal employ it normally requires some previous training and tends to crusade centre strain.
• The cross-eyed viewing method swaps the left and right eye images so that they will be correctly seen cross-eyed, the left centre viewing the image on the right and vice versa. The fused three-dimensional image appears to exist smaller and closer than the actual images, so that large objects and scenes appear miniaturized. This method is usually easier for freeviewing novices. Equally an aid to fusion, a fingertip can be placed just below the segmentation between the ii images, then slowly brought direct toward the viewer'southward eyes, keeping the eyes directed at the fingertip; at a certain distance, a fused iii-dimensional image should seem to exist hovering but above the finger. Alternatively, a slice of paper with a small-scale opening cutting into information technology can be used in a similar way; when correctly positioned betwixt the image pair and the viewer's eyes, information technology will seem to frame a small three-dimensional epitome.

Prismatic, self-masking glasses are now beingness used by some cantankerous-eyed-view advocates. These reduce the degree of convergence required and allow large images to exist displayed. However, any viewing aid that uses prisms, mirrors or lenses to aid fusion or focus is but a type of stereoscope, excluded past the customary definition of freeviewing.

Stereoscopically fusing two separate images without the aid of mirrors or prisms while simultaneously keeping them in sharp focus without the help of suitable viewing lenses inevitably requires an unnatural combination of eye vergence and accommodation. Elementary freeviewing therefore cannot accurately reproduce the physiological depth cues of the real-globe viewing experience. Different individuals may experience differing degrees of ease and condolement in achieving fusion and skilful focus, as well equally differing tendencies to centre fatigue or strain.

Autostereogram [edit]

An autostereogram is a unmarried-image stereogram (Sis), designed to create the visual illusion of a three-dimensional (3D) scene within the man brain from an external 2-dimensional prototype. In order to perceive 3D shapes in these autostereograms, one must overcome the normally automatic coordination between focusing and vergence.

Stereoscope and stereographic cards [edit]

The stereoscope is essentially an instrument in which two photographs of the same object, taken from slightly different angles, are simultaneously presented, 1 to each eye. A unproblematic stereoscope is limited in the size of the epitome that may be used. A more complex stereoscope uses a pair of horizontal periscope-like devices, assuasive the utilise of larger images that tin can present more detailed information in a wider field of view. One can purchase historical stereoscopes such as Holmes stereoscopes equally antiques. Many stereo photography artists like Jim Naughten and Rebecca Hackemann also make their own stereoscopes.

Transparency viewers [edit]

A View-Master Model E of the 1950s

Some stereoscopes are designed for viewing transparent photographs on movie or glass, known every bit transparencies or diapositives and commonly called slides. Some of the primeval stereoscope views, issued in the 1850s, were on glass. In the early on 20th century, 45x107 mm and 6x13 cm glass slides were common formats for amateur stereo photography, especially in Europe. In later years, several film-based formats were in employ. The best-known formats for commercially issued stereo views on film are Tru-Vue, introduced in 1931, and View-Main, introduced in 1939 and still in production. For amateur stereo slides, the Stereo Realist format, introduced in 1947, is past far the well-nigh common.

Caput-mounted displays [edit]

An HMD with a carve up video source displayed in front of each center to achieve a stereoscopic effect

The user typically wears a helmet or glasses with ii small LCD or OLED displays with magnifying lenses, one for each center. The engineering science can be used to show stereo films, images or games, but information technology tin as well be used to create a virtual display. Head-mounted displays may also exist coupled with head-tracking devices, allowing the user to "look around" the virtual world by moving their head, eliminating the demand for a dissever controller. Performing this update quickly enough to avoid inducing nausea in the user requires a great amount of computer image processing. If six centrality position sensing (management and position) is used then wearer may movement about within the limitations of the equipment used. Owing to rapid advancements in calculator graphics and the continuing miniaturization of video and other equipment these devices are starting time to become bachelor at more reasonable cost.

Head-mounted or wearable glasses may exist used to view a see-through image imposed upon the existent world view, creating what is called augmented reality. This is done by reflecting the video images through partially cogitating mirrors. The real globe view is seen through the mirrors' cogitating surface. Experimental systems have been used for gaming, where virtual opponents may peek from existent windows equally a role player moves about. This blazon of system is expected to have wide application in the maintenance of complex systems, equally it can give a technician what is finer "x-ray vision" by combining calculator graphics rendering of hidden elements with the technician's natural vision. Additionally, technical information and schematic diagrams may be delivered to this same equipment, eliminating the demand to obtain and conduct bulky paper documents.

Augmented stereoscopic vision is also expected to take applications in surgery, as it allows the combination of radiographic information (CAT scans and MRI imaging) with the surgeon's vision.

Virtual retinal displays [edit]

A virtual retinal display (VRD), too known as a retinal scan display (RSD) or retinal projector (RP), not to be confused with a "Retina Display", is a display applied science that draws a raster paradigm (like a telly picture) directly onto the retina of the middle. The user sees what appears to be a conventional display floating in infinite in front of them. For true stereoscopy, each eye must exist provided with its own discrete display. To produce a virtual display that occupies a usefully big visual angle but does not involve the use of relatively big lenses or mirrors, the light source must exist very shut to the centre. A contact lens incorporating ane or more semiconductor light sources is the form most commonly proposed. As of 2013, the inclusion of suitable light-axle-scanning means in a contact lens is still very problematic, as is the alternative of embedding a reasonably transparent array of hundreds of thousands (or millions, for Hard disk resolution) of accurately aligned sources of collimated light.

A pair of LC shutter glasses used to view XpanD 3D films. The thick frames conceal the electronics and batteries.

RealD circular polarized glasses

3D viewers [edit]

"3D viewer" redirects here. For Microsoft Store app bundled with Windows x, see Microsoft 3D Viewer.

At that place are ii categories of 3D viewer technology, active and passive. Active viewers have electronics which interact with a display. Passive viewers filter abiding streams of binocular input to the advisable eye.

Active [edit]

Shutter systems [edit]

Functional principle of active shutter 3D systems

A shutter organization works by openly presenting the prototype intended for the left center while blocking the right centre'southward view, so presenting the right-eye prototype while blocking the left centre, and repeating this and then apace that the interruptions do not interfere with the perceived fusion of the two images into a single 3D image. It generally uses liquid crystal shutter glasses. Each eye's glass contains a liquid crystal layer which has the property of becoming dark when voltage is applied, beingness otherwise transparent. The glasses are controlled past a timing signal that allows the glasses to alternately darken over one eye, and and then the other, in synchronization with the refresh rate of the screen. The main drawback of active shutters is that near 3D videos and movies were shot with simultaneous left and correct views, so that it introduces a "time parallax" for annihilation side-moving: for instance, someone walking at iii.4 mph volition exist seen twenty% as well close or 25% too remote in the most current case of a 2x60 Hz projection.

Passive [edit]

Polarization systems [edit]

Functional principle of polarized 3D systems

To nowadays stereoscopic pictures, two images are projected superimposed onto the aforementioned screen through polarizing filters or presented on a display with polarized filters. For projection, a argent screen is used and so that polarization is preserved. On most passive displays every other row of pixels is polarized for i eye or the other.^[20] This method is besides known as being interlaced. The viewer wears low-toll eyeglasses which likewise contain a pair of opposite polarizing filters. As each filter only passes low-cal which is similarly polarized and blocks the opposite polarized low-cal, each heart merely sees one of the images, and the consequence is accomplished.

Interference filter systems [edit]

This technique uses specific wavelengths of red, green, and blueish for the right eye, and different wavelengths of red, dark-green, and bluish for the left eye. Eyeglasses which filter out the very specific wavelengths allow the wearer to see a total color 3D prototype. Information technology is besides known as spectral rummage filtering or wavelength multiplex visualization or super-anaglyph. Dolby 3D uses this principle. The Omega 3D/Panavision 3D system has also used an improved version of this technology^[21] In June 2012 the Omega 3D/Panavision 3D system was discontinued by DPVO Theatrical, who marketed it on behalf of Panavision, citing ″challenging global economic and 3D market weather″.

Color anaglyph systems [edit]

Anaglyph 3D is the name given to the stereoscopic 3D effect achieved by means of encoding each centre's prototype using filters of different (ordinarily chromatically opposite) colors, typically cherry and cyan. Red-cyan filters tin be used because our vision processing systems use red and cyan comparisons, also every bit blue and yellow, to make up one's mind the color and contours of objects. Anaglyph 3D images contain two differently filtered colored images, i for each eye. When viewed through the "color-coded" "anaglyph glasses", each of the two images reaches i eye, revealing an integrated stereoscopic image. The visual cortex of the encephalon fuses this into perception of a three dimensional scene or composition.^[22]

Chromadepth system [edit]

ChromaDepth glasses with prism-like film

The ChromaDepth procedure of American Paper Optics is based on the fact that with a prism, colors are separated by varying degrees. The ChromaDepth eyeglasses contain special view foils, which consist of microscopically small prisms. This causes the image to be translated a sure amount that depends on its color. If one uses a prism foil at present with one eye only non on the other eye, so the 2 seen pictures – depending upon color – are more than or less widely separated. The brain produces the spatial impression from this departure. The reward of this technology consists in a higher place all of the fact that i tin regard ChromaDepth pictures also without eyeglasses (thus 2-dimensional) problem-free (unlike with two-color anaglyph). Withal the colors are only limitedly selectable, since they contain the depth data of the movie. If 1 changes the colour of an object, then its observed distance will too exist inverse.^{[ citation needed ]}

Pulfrich method [edit]

The Pulfrich effect is based on the miracle of the homo middle processing images more slowly when there is less light, as when looking through a dark lens.^[23] Considering the Pulfrich effect depends on motion in a particular management to instigate the illusion of depth, it is not useful as a general stereoscopic technique. For example, it cannot be used to show a stationary object evidently extending into or out of the screen; similarly, objects moving vertically will not be seen equally moving in depth. Incidental movement of objects volition create spurious artifacts, and these incidental furnishings volition exist seen every bit bogus depth non related to actual depth in the scene.

Over/nether format [edit]

Stereoscopic viewing is achieved past placing an epitome pair one above one some other. Special viewers are fabricated for over/under format that tilt the right eyesight slightly up and the left eyesight slightly downwards. The most common 1 with mirrors is the View Magic. Another with prismatic glasses is the KMQ viewer.^[24] A contempo usage of this technique is the openKMQ project.^[25]

Other display methods without viewers [edit]

Autostereoscopy [edit]

The Nintendo 3DS uses parallax bulwark autostereoscopy to display a 3D paradigm.

Autostereoscopic display technologies use optical components in the display, rather than worn past the user, to enable each middle to see a different image. Because headgear is not required, it is besides called "spectacles-free 3D". The optics carve up the images directionally into the viewer's eyes, so the display viewing geometry requires limited caput positions that volition achieve the stereoscopic effect. Automultiscopic displays provide multiple views of the same scene, rather than just two. Each view is visible from a different range of positions in front of the brandish. This allows the viewer to motility left-right in front end of the brandish and see the right view from any position. The engineering includes two broad classes of displays: those that use head-tracking to ensure that each of the viewer's two eyes sees a different prototype on the screen, and those that display multiple views and then that the display does not need to know where the viewers' eyes are directed. Examples of autostereoscopic displays engineering include lenticular lens, parallax barrier, volumetric display, holography and lite field displays.

Holography [edit]

Light amplification by stimulated emission of radiation holography, in its original "pure" grade of the photographic manual hologram, is the just technology nonetheless created which can reproduce an object or scene with such complete realism that the reproduction is visually duplicate from the original, given the original lighting conditions.^{[ citation needed ]} It creates a light field identical to that which emanated from the original scene, with parallax about all axes and a very wide viewing angle. The center differentially focuses objects at different distances and subject item is preserved downwardly to the microscopic level. The consequence is exactly like looking through a window. Unfortunately, this "pure" class requires the field of study to be laser-lit and completely motionless—to inside a modest fraction of the wavelength of low-cal—during the photographic exposure, and laser light must be used to properly view the results. Nearly people take never seen a laser-lit manual hologram. The types of holograms commonly encountered have seriously compromised paradigm quality and so that ordinary white light tin be used for viewing, and not-holographic intermediate imaging processes are nigh always resorted to, equally an alternative to using powerful and hazardous pulsed lasers, when living subjects are photographed.

Although the original photographic processes have proven impractical for full general use, the combination of calculator-generated holograms (CGH) and optoelectronic holographic displays, both under evolution for many years, has the potential to transform the half-century-old pipe dream of holographic 3D boob tube into a reality; and then far, however, the large corporeality of calculation required to generate just 1 detailed hologram, and the huge bandwidth required to transmit a stream of them, accept confined this technology to the enquiry laboratory.

In 2013, a Silicon Valley company, LEIA Inc, started manufacturing holographic displays well suited for mobile devices (watches, smartphones or tablets) using a multi-directional backlight and assuasive a wide full-parallax angle view to run into 3D content without the need of glasses.^[26]

Volumetric displays [edit]

Volumetric displays use some concrete machinery to brandish points of light inside a volume. Such displays employ voxels instead of pixels. Volumetric displays include multiplanar displays, which have multiple display planes stacked upwardly, and rotating panel displays, where a rotating panel sweeps out a volume.

Other technologies have been developed to projection light dots in the air above a device. An infrared laser is focused on the destination in infinite, generating a small bubble of plasma which emits visible light.

Integral imaging [edit]

Integral imaging is a technique for producing 3D displays which are both autostereoscopic and multiscopic, meaning that the 3D prototype is viewed without the use of special glasses and different aspects are seen when it is viewed from positions that differ either horizontally or vertically. This is achieved by using an array of microlenses (alike to a lenticular lens, but an X–Y or "fly's eye" array in which each lenslet typically forms its own image of the scene without aid from a larger objective lens) or pinholes to capture and display the scene every bit a 4D lite field, producing stereoscopic images that exhibit realistic alterations of parallax and perspective when the viewer moves left, right, upwardly, downwardly, closer, or further away.

Wiggle stereoscopy [edit]

Wiggle stereoscopy is an image display technique accomplished by apace alternating display of left and right sides of a stereogram. Institute in animated GIF format on the web, online examples are visible in the New-York Public Library stereogram collection. The technique is also known equally "Piku-Piku".^[27]

Stereo photography techniques [edit]

For full general purpose stereo photography, where the goal is to duplicate natural human vision and requite a visual impression as close equally possible to actually being at that place, the correct baseline (distance between where the right and left images are taken) would be the aforementioned as the distance between the eyes.^[28] When images taken with such a baseline are viewed using a viewing method that duplicates the conditions under which the picture is taken, then the upshot would be an image much the same as that which would exist seen at the site the photo was taken. This could exist described as "ortho stereo."

Withal, there are situations in which it might be desirable to apply a longer or shorter baseline. The factors to consider include the viewing method to be used and the goal in taking the picture. The concept of baseline also applies to other branches of stereography, such as stereo drawings and calculator generated stereo images, but it involves the point of view chosen rather than bodily physical separation of cameras or lenses.

Stereo window [edit]

The concept of the stereo window is always of import, since the window is the stereoscopic paradigm of the external boundaries of left and right views constituting the stereoscopic image. If any object, which is cut off past lateral sides of the window, is placed in front of information technology, an effect results that is unnatural and is undesirable, this is called a "window violation". This can best be understood by returning to the analogy of an actual physical window. Therefore, there is a contradiction between two dissimilar depth cues: some elements of the paradigm are hidden by the window, then that the window appears as closer than these elements, and the same elements of the epitome announced equally closer than the window. So that the stereo window must always be adjusted to avoid window violations.

Some objects can be seen in forepart of the window, as far as they don't reach the lateral sides of the window. But these objects can non be seen as too close, since there is always a limit of the parallax range for comfy viewing.

If a scene is viewed through a window the entire scene would normally be behind the window, if the scene is distant, it would be some altitude behind the window, if information technology is nearby, it would appear to be just beyond the window. An object smaller than the window itself could even get through the window and appear partially or completely in front of it. The same applies to a part of a larger object that is smaller than the window. The goal of setting the stereo window is to duplicate this result.

Therefore, the location of the window versus the whole of the image must be adjusted so that most of the epitome is seen across the window. In the example of viewing on a 3D Television set gear up, it is easier to place the window in front of the image, and to permit the window in the aeroplane of the screen.

On the opposite, in the case of projection on a much larger screen, it is much better to prepare the window in front of the screen (it is called "floating window"), for case so that it is viewed most two meters abroad by the viewers sit in the first row. Therefore, these people will normally see the groundwork of the epitome at the space. Of course the viewers seated beyond will see the window more remote, simply if the image is made in normal conditions, so that the kickoff row viewers run across this background at the space, the other viewers, seated backside, will also run across this groundwork at the infinite, since the parallax of this background is equal to the average human being interocular.

The entire scene, including the window, tin exist moved backwards or frontwards in depth, by horizontally sliding the left and right eye views relative to each other. Moving either or both images away from the center will bring the whole scene away from the viewer, whereas moving either or both images toward the heart will move the whole scene toward the viewer. This is possible, for instance, if two projectors are used for this projection.

In stereo photography window adjustments is accomplished by shifting/cropping the images, in other forms of stereoscopy such as drawings and estimator generated images the window is built into the blueprint of the images every bit they are generated.

The images can exist cropped creatively to create a stereo window that is not necessarily rectangular or lying on a flat aeroplane perpendicular to the viewer'south line of sight. The edges of the stereo frame can be direct or curved and, when viewed in 3D, can flow toward or away from the viewer and through the scene. These designed stereo frames tin assist emphasize certain elements in the stereo prototype or tin exist an artistic component of the stereo paradigm.

Uses [edit]

While stereoscopic images have typically been used for entertainment, including stereographic cards, 3D films, 3D tv set, stereoscopic video games,^[29] printings using anaglyph and pictures, posters and books of autostereograms, there are also other uses of this technology.

Art [edit]

Salvador Dalí created some impressive stereograms in his exploration in a diversity of optical illusions. Other stereo artists include Zoe Beloff, Christopher Schneberger, Rebecca Hackemann, William Kentridge, and Jim Naughten.^[30] Carmine-and-cyan anaglyph stereoscopic images have also been painted by mitt.^[31]

Education [edit]

In the 19th century, it was realized that stereoscopic images provided an opportunity for people to experience places and things far abroad, and many tour sets were produced, and books were published assuasive people to larn about geography, science, history, and other subjects.^[32] Such uses continued till the mid-20th century, with the Keystone View Company producing cards into the 1960s.

Space exploration [edit]

The Mars Exploration Rovers, launched by NASA in 2003 to explore the surface of Mars, are equipped with unique cameras that allow researchers to view stereoscopic images of the surface of Mars.

The 2 cameras that make up each rover'southward Pancam are situated 1.5m above the ground surface, and are separated by 30 cm, with i degree of toe-in. This allows the image pairs to exist made into scientifically useful stereoscopic images, which can be viewed equally stereograms, anaglyphs, or processed into 3D estimator images.^[33]

The power to create realistic 3D images from a pair of cameras at roughly human being-height gives researchers increased insight every bit to the nature of the landscapes being viewed. In environments without hazy atmospheres or familiar landmarks, humans rely on stereoscopic clues to gauge distance. Single camera viewpoints are therefore more difficult to interpret. Multiple camera stereoscopic systems like the Pancam address this problem with unmanned space exploration.

Clinical uses [edit]

Stereogram cards and vectographs are used past optometrists, ophthalmologists, orthoptists and vision therapists in the diagnosis and treatment of binocular vision and accommodative disorders.^[34]

Mathematical, scientific and applied science uses [edit]

Stereopair photographs provided a way for 3-dimensional (3D) visualisations of aerial photographs; since about 2000, 3D aeriform views are mainly based on digital stereo imaging technologies. One issue related to stereo images is the corporeality of disk infinite needed to save such files. Indeed, a stereo image usually requires twice as much space as a normal epitome. Recently, estimator vision scientists tried to find techniques to attack the visual redundancy of stereopairs with the aim to ascertain compressed version of stereopair files.^{[35] [36]} Cartographers generate today stereopairs using computer programs in order to visualise topography in three dimensions.^[37] Computerised stereo visualisation applies stereo matching programs.^[38] In biology and chemistry, complex molecular structures are oft rendered in stereopairs. The same technique can besides be applied to any mathematical (or scientific, or applied science) parameter that is a function of two variables, although in these cases it is more mutual for a three-dimensional issue to be created using a 'distorted' mesh or shading (equally if from a afar light source).

Come across also [edit]

• Deject stereoscopy

References [edit]

1. ^ "The Kaiser (Emperor) Panorama". 9 June 2012.
2. ^ ^{a b} The Logical Arroyo to Seeing 3D Pictures. www.vision3d.com by Optometrists Network. Retrieved 2009-08-21
3. ^ στερεός Tufts.edu, Henry George Liddell, Robert Scott, A Greek-English Dictionary, on Perseus Digital Library
4. ^ σκοπέω, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus Digital Library
5. ^ Exercises in Three Dimensions: Virtually 3D, Tom Lincoln, 2011
6. ^ Flying Simulation, J. M. Rolfe and M. J. Staples, Cambridge University Press, 1986, page 134
7. ^ Exercises in Three Dimensions, Tom Lincoln, 2011
8. ^ ^{a b} Contributions to the Physiology of Vision.—Part the First. On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision. By CHARLES WHEATSTONE, F.R.Southward., Professor of Experimental Philosophy in King's Higher, London. Stereoscopy.com
9. ^ Welling, William. Photography in America, page 23
10. ^ International Stereoscopic Union, 2006, "Stereoscopy", Numbers 65–72, p.18
11. ^ Stereo Realist Manual, p. 375.
12. ^ Stereo Realist Manual, pp. 377–379.
13. ^ Fay Huang, Reinhard Klette, and Karsten Scheibe: Panoramic Imaging (Sensor-Line Cameras and Laser Range-Finders). Wiley & Sons, Chichester, 2008
14. ^ Dornaika, F.; Hammoudi, Yard (2009). Extracting 3D Polyhedral Building Models from Aerial Images using a Characterless and Directly Approach (PDF). Machine Vision Applications. Vol. Proc. IAPR/MVA. Retrieved 26 September 2010.
15. ^ ^{a b} How To Freeview Stereo (3D) Images. Greg Erker. Retrieved 2009-08-21
16. ^ "Eyecare Trust". Eyecare Trust. Retrieved 29 March 2012.
17. ^ "Daily Telegraph Newspaper". The Daily Telegraph. Archived from the original on 12 January 2022. Retrieved 29 March 2012.
18. ^ "Understanding Requirements for Loftier-Quality 3D Video: A Exam in Stereo Perception". 3droundabout.com. xix Dec 2011. Retrieved 29 March 2012.
19. ^ How to View Photos on This Site. Stereo Photography – The World in 3D. Retrieved 2009-08-21
20. ^ Tseng, Belle; Anastassiou, Dimitris. "Compatible Video Coding of Stereoscopic Sequences using MPEG-ii'south Scalability and Interlaced Construction" (PDF). Columbia Academy. Retrieved 8 July 2014.
21. ^ "Seeing is believing""; Movie house Technology, Vol 24, No.1 March 2011
22. ^ "Exercises in Three Dimensions: Almost 3D".
23. ^ O'Doherty, M; Flitcroft, D I (1 August 2007). "An unusual presentation of optic neuritis and the Pulfrich phenomenon". Periodical of Neurology, Neurosurgery & Psychiatry. 78 (8): 906–907. doi:x.1136/jnnp.2006.094771. ISSN 0022-3050. PMC2117749. PMID 17635984.
24. ^ "Glossary". 8 June 2012.
25. ^ "openKMQ". 8 June 2012. Archived from the original on 5 March 2009.
26. ^ Beausoleil, Raymond Grand.; Brug, Jim; Fiorentino, Marco; Vo, Sonny; Tran, Tho; Peng, Zhen; Fattal, David (March 2013). "A multi-directional backlight for a broad-angle, glasses-costless 3-dimensional display". Nature. 495 (7441): 348–351. Bibcode:2013Natur.495..348F. doi:10.1038/nature11972. ISSN 1476-4687. PMID 23518562. S2CID 4424212.
27. ^ Curtin, Dennis P. "ShortCourses-Stereo Photography-Simulated 3D—Wiggle 3D". www.shortcourses.com.
28. ^ DrT (25 February 2008). "Dr. T". Drt3d.blogspot.com. Retrieved four March 2012.
29. ^ Banks, Martin S.; Read, Jenny R.; Allison, Robert S.; Watt, Simon J. (June 2011). "Stereoscopy and the Human Visual System". SMPTE 2d Annual International Conference on Stereoscopic 3D for Media and Entertainment. New York, NY, U.s.: IEEE. 121 (4): 2–31. doi:x.5594/M001418. ISBN9781614829515. PMC3490636. PMID 23144596.
30. ^ Horibuchi, Southward. (1994). Salvador Dalí: the stereo pair creative person. In Horibuchi, S. (Ed.), Stereogram (pp.9, pp.42). San Francisco: Cadence Books. ISBN 0-929279-85-9
31. ^ "Tom Lincoln - Exercises in Three Dimensions".
32. ^ Academy of Virginia The Stereoscope in America, accessed 21 March 2009.
33. ^ "Pancam technical brief" (PDF). Cornell University. Retrieved xxx June 2006.
34. ^ Bartiss, OD MD, Michael (25 January 2005). "Convergence Insufficiency". WebMD. Retrieved 30 June 2006.
35. ^ "Algorithm for stereoscopic image pinch".
36. ^ Ortis, Alessandro; Rundo, Francesco; Di Giore, Giuseppe; Battiato, Sebastiano (2013). "Adaptive Pinch of Stereoscopic Images" (PDF). Image Analysis and Processing – ICIAP 2013. Lecture Notes in Information science. Vol. 8156. pp. 391–399. doi:10.1007/978-three-642-41181-6_40. ISBN978-three-642-41180-9.
37. ^ David F. Watson (1992). Contouring. A Guide to the Assay and Display of Spatial Data (with programs on diskette). In: Daniel F. Merriam (Ed.); Computer Methods in the Geosciences; Pergamon / Elsevier Science, Amsterdam; 321 pp. ISBN 0-08-040286-0
38. ^ Reinhard Klette (2014). "Concise Computer Vision" (see Chapter 8 for stereo matching). Springer, London; 429 pp. ISBN 978-one-4471-6319-0

Bibliography [edit]

• Simmons, Gordon (March–April 1996). "Clarence G. Henning: The Man Backside the Macro". Stereo World. 23 (ane): 37–43.
• Willke, Mark A.; Zakowski, Ron (March–April 1996). "A Shut Look into the Realist Macro Stereo System". Stereo World. 23 (1): 14–35.
• Morgan, Willard D.; Lester, Henry One thousand. (October 1954). Stereo Realist Manual. and 14 contributors. New York: Morgan & Lester. Bibcode:1954srm..book.....Grand. OCLC 789470.

Farther reading [edit]

• Scott B. Steinman, Barbara A. Steinman and Ralph Philip Garzia. (2000). Foundations of Binocular Vision: A Clinical perspective. McGraw-Hill Medical. ISBN 0-8385-2670-5

External links [edit]

Archival collections [edit]

• Guide to the Edward R. Frank Stereograph Collection. Special Collections and Archives, The UC Irvine Libraries, Irvine, California.
• Niagara Falls Stereo Cards RG 541 Brock University Library Digital Repository

Other [edit]

• Stereoscopy at Curlie
• Durham Visualization Laboratory stereoscopic imaging methods and software tools
• Academy of Washington Libraries Digital Collections Stereocard Collection
• Stereographic Views of Louisville and Beyond, 1850s–1930 from the University of Louisville Libraries
• Stereoscopy on Flickr
• American University in Cairo Rare Books and Special Collections Digital Library Underwood & Underwood Egypt Stereoviews Drove
• Views of California and the West, ca. 1867–1903, The Bancroft Library
• Museum exhibition on the history of stereographs and stereoscopes (1850–1930)
• 2 stereoscopic selfies from 1890

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