2D is the shorter and easily recognizable way of writing two dimensional. 2D relates to an object or image which has no depth. Instead it only has two dimensions, width and height.
2D signal processing
Signal processing is a term which is used when describing 3D and 2D signals which receive the same processing pattern, and the systems processor does not need to know what type of signal (2D or 3D) is being processed.
Similar to 2D, 3D stands for three dimensional. A 3D object appears to have three dimensions; width, height, and depth.
3D adjustment setting
Adjusting the settings simply changes the depth of any objects that are visible on a 3D view screen.
A 3D DVD is quite simply just a DVD film recorded with 3D technology, and it allows the on screen actions to appear as if they are reaching out of the screen.
3D format conversion
Is the process of changing one 3D video format into another.
Is a process within which the computer will produce an image based on the 3D data which has been inputted to the system.
Viewing an image in 3D with the correct glasses to experience stereoscopic vision and binocular depth perception.
Is the process of leveling, scaling and orientating the control points of a proportionately oriented stereoscopic model
Accidental stereo effects
These effects are found when supposedly identical parallel pictures are fused together. (A great example of this can be seen on postage stamps, where the irregularities in printing cause a limited 3D effect.)
This refers to the eyes refocusing on another object as the viewers vision shifts from one distance plane to another.
Accommodation -vergence relationship
This learned relationship which was established through early experiences between the verging and focusing of the eyes when looking at one particular subject in the visual world. This is normally called the convergence/accommodation relationship or the accommodation convergence relationship.
Is caused when the eyes change focus whilst the they converge. The accommodation-convergence link is something that needs to be overcome in stereo viewing as the focus remains unchanged on the plane of the constituent flat images.
Refers to the human eyes ability to automatically and repeatedly change focus from one distance to another. Accommodative facility is usually measured by use of ‘flipper lenses’. The measurement of each eye is usually made and then followed by comparing the performance of one eye against both eyes working together.
Is a unique method of stereoscopic display which permits each eye to see the left-eye/right-eye images in an extremely rapid succession by using powered shutter glasses which function alternatively. This is done to in a very quick succession of flashes to create the impression of depth.
The distance between the left and right camera positions from which the stereo images are taken.
Along track stereo pair
Refers to a pair of images that are acquired from different viewing angles as the plane moves along its flight path.
Amblyopia is a visual defect that affects around 3 out of every 100 children in the U.S.A. Amblyopia, also known as ‘Lazy Eye’, involves lowered visual clarity and/or weakened muscle control in just one eye. The result of suffering from Lazy Eye is often a loss of binocular depth perception and stereoscopic vision.
Is a type of stereogram that can be printed, projected if televised. With Anaglyph technology the two images are superimposed but then are separated, so that each eye will see only the desired image. The use of differently colored filters and 3D glasses (usually red and cyan, or red and green) make the effect work. Without the correct glasses and using just the naked eye the effect will not work and the image will look doubled and blurry. Traditionally, the left eye image is printed in red and the right eyes image in green ink.
An analogue stereoplotter will implement all corrections and orientations with optical and mechanical means.
An analytical stereoplotter is a stereo comparator which is encoded so that coordinate measurements on images can be moved to a computer and converted into a digital format. By using hardcopies, features and contours are digitized and then plotted out from the computer.
These devices (Analyzers) are placed in front of the eyes with intention of separating the left and right eyes images. Usually used when the image is being projected, these typically are polarizing glasses, liquid crystal shutters or anaglyph spectacles.
Refers to the distance between the centers or of the openings in the cameras aperture. The distance is usually 71.25 mm in many stereo cameras using a 5-perforation format. However, cameras in a 7-perforation format typically use an aperture separation of 63.5 mm.
Application Programming Interface (API)
An API is a standard programming interface that allows developers to write their applications to a specific standard without having any major knowledge about the hardware’s implementations. A benefit is that a single application can comfortably run on a variety of hardware platforms without the need for it to be rewritten for each of those specific platforms. By intercepting the API’s instructions, the software driver for the hardware translates its instructions into specific instructions which are created for the hardware. Open GL and DirectX APIs can also emulate hardware functions to ensure that an application will work even if the hardware platform is missing a feature.
Astigmatism is a distortion in the vision which is caused due to an irregular shape of the eye or its components.
This normally describes a stereogram that is designed to be viewed by people without the use of any special equipment in front of the eyes. (For example: a single-image random-dot stereogram.)
Is a term used when referring to glasses free 3D.
Is the gap between the left and right lenses when taking a stereoscopic photograph. A regular stereo base is thought to be one similar to the distance between your left and right eye (65mm).
Base height ratio
The recommended base height ratio is 1:6. This term is used for stereo images and it refers to the ratio between the base distance and the camera distance.
Baseline simply refers to the distance you move between the left and right pictures when you are taking them.
This device consists of prisms or/and mirrors that can simply be attached to a mono camera, and the effect produces two parallel images within a single frame. It is also more accurately known as an ‘Image-Splitter’, due to the fact that it does not actually split an individual beam into components. The rays of light which form the left and right images as they enter the cameras lens and cross over, means that the recorded images end up in the correct configuration for stereo viewing.
Is simply the definition for the use of both eyes at once.
Binocular depth perception
B.D.P is the result of successful stereo vision. Successful stereo vision requires the ability to visually perceive 3D space; whilst at same time being able to judge distances between objects.
A binocular skill is a term used to cover a wide range of skills that are required when using both eyes together to take in an image. This includes the efficient use of the eyes to see in a three dimensional space (stereoscopic vision). Binocular skills do however come with some difficulty, for example; focusing, eye movement accuracy, eye alignment, all these factors can reduce the speed of processing information.
This device is a simple two-lensed piece of equipment for viewing pictures where using both eyes gives an easier viewing experience and enhances the impression of depth.
Refers to both eyes working together smoothly and simultaneously.
Binocular vision disability
Is a visual defect in which both eyes cease to work together which results in a partial or even a total loss of stereoscopic vision and binocular depth perception. It is said that around 12% of the population has some form of binocular vision disability. The most commonly known forms of binocular vision disabilities are Amblyopia and strabismus.
Card boarding is usually the result of an insufficient depth resolution and it causes objects to appear as if they lack solidity and they are a cardboard cutout.
The 1985 Wheatstone stereoscope by L.Cazes has had a new development. The new development on the Wheatstone stereoscope has incorporated additional angled mirrors to help view large images similar to the type used in aerial surveying.
method of stereo picture taking is an extremely harder way to get positive results. The method involves taking an ordinary camera and capturing a picture for both the left and right eye by simply moving the cameras position from left to right.
Chromatic stereoscopy Chromostereopsis
This impression of depth is a result of viewing a spectrum of various colored images through some form of light-bending device (e.g. a prism or embossed ‘holographic’ filter’. It is caused due to variations in the different bends, depending on the wavelength of the light from various colors, known as chromatic dispersion. If light bending devices such as these were to be placed in front of each eye but then arranged for displays of differing colors in opposite directions, an impressive 3D effect will be seen. This effect can also be achieved by the natural eyes lenses if a person was to view a planar image with strong differing colors.
Is an effect obtained in time-lapse photography when there has been a change in the subject.
Is a device that is named after its inventor, just like many other. The device is like a rectangular mounted lens hood on a twin-lens stereo attachment which is used with a mono camera to prevent light spilling into the unwanted areas.
Column interleaved format
This is the three dimensional format which is used by the specialist VR-4200 projector. The left and right image data is encoded on different columns on the display.
Focusing the two camera lenses on different planes of the subject matter in order to increase the depth of field perceived in viewing the resulting stereogram.In order to increase the depth of field when viewing the stereogram two camera lenses can be focused on different planes of the subject.
To make sure that you can get accurate measurements from a stereo pair, there needs to be at least 6 control points situated around or on the object being recorded. Every point must have three dimensional coordinates which relate to a single origin. The points then show a 3D reference system with which the object being recorded can be related too.
Control points are marks of established three dimensional coordinates that are visible on both stereo images, and are used in order to perform the absolute orientation.
Refers to a person’s ability to turn both eyes to turn inwards together. Doing so enables both eyes to be fixated the exact same point. Convergence is an essential skill in order to pay adequate attention to close objects and to be able to read.. Convergence is required to be held for a long period of time, with good eye control and binocular skills, it is essential to be able to focus on things further away. This is called divergence. Vital skills for learning and reading depend upon the eye being able to make a rapid convergence and divergence. This term has been used to describe the movement of left and right image fields or the rotation of cameras.
Correlation is a process that involves locating pixels which represent the same point in a pair of stereo images, so that you can create a disparity image. Correlation is also known as the ‘matching process’. The two pixels when correlated have come to be known as the homologous points.
Also known as the homologous or conjugate points. These points within an image on the left and right fields refer to the same point on the object. The gap between the points on the screen is defined as a ‘parallax’.
Cross-eyed free-vision fusion viewing method
This is a method that cannot be used on the majority of stereo cards because they are printed in a parallel format. It is a method of free viewing stereo pairs within which the eyes intended images are crossed over, so the left eyes image is place on the right side of a stereo pair and the right eye becomes the left. This kind of viewing is said to be easier to learn than the other parallel method and it can successfully be done with much larger images.
Cross talk is caused by the incomplete isolation of the left and right image channels, and one image leaks into the other. The effect makes it look like a double exposure.
This term derives from the legendary single eyed monster with one eye centered in his forehead, the Cyclops. And simply refers to the singular three dimensional mental image gained by the brains joining together of each eyes individual view.
Also referred to as stereo vision and stereopsis. Depth Perception refers to the ability to see in 3D to allow us to be able to judge the distances of objects and features.
Depth Range is a definition that can be applied to stereoscopic images created using cameras.
Diplopia, otherwise known as ‘Double Vision’, is caused in stereo viewing when the left and right homologues remain separated rather than being fused into one whole, single image.
A hardware abstraction layer API from Microsoft that is integral to the Windows operating system. The DirectX hardware abstraction layer API from Microsoft is integral to any Windows operating system. The Direct X standard includes Direct3D, DirectSound, DirectDraw, Direct Video, DirectPlay, and DirectInput. NVIDIA technologies were licensed by Microsoft for the latest version of the Direct X technology, in order to add programmability to the API.
This term refers to a set of images that fail to work as a stereogram due to reasons such as, masking, mismatched camera lenses or even due to distortion.
This is the distance between points on overlaid retinas, sometimes known as retinal disparity. A correlating term for the display screen is a ‘parallax’.
The parallax between images depicting the same scene, however it was acquired from two different viewing angles. The disparity between homologous points is used to compute the elevation.
This is caused by the accidental, or on some occasions deliberate misalignment of homologues in a stereogram. When accidentally done it is often due to the movement of two frames on the mount from their specified positions.
An image becomes distorted when any change in the original shape of an image occurs, and changes its appearance from the ideal/perfect form. In stereo, it is usually due to an over exaggeration or reduction to the front to back dimension.
Refers to the human eyes ability to turn outwards together allowing them to both look further away. Divergence is the exact opposite of convergence. As discussed in convergence, it is essential for efficient learning and general visual performance .
Drivers are simply just software that enables the communication between a computers graphics processor and the rest of the system. Software drivers are constantly updated to help improve a systems performance, quality, and to enable many new features.
Are known as depth cues, which are appreciated by a person using only one eye. Also known as ‘monocular’ cues. These cues include, motion parallax interposition, geometric perspective, aerial perspective, shading, relative size and textural gradient.
False stereo effects
These effects are caused in aquatic and snow scenes, it happens when one lens picks up a reflection which the other lens misses and this image is then fused with a different reflection picked up by the other lens. It can also be caused by subject movement between two separate, sequential exposures. For example; the drifting of clouds.
This is the feature in a stereo image that will appear to be the farthest distance from the viewer.
Field of view
The field of view is the angle with which a lens can accept light. It is usually measured in degrees. For example, 175° is the horizontal field of view for the human eye.
When talking about field sequential in the context of cinema-stereoscopy, it is defined as the rapid alternation of the right and left perspective views that are projected onto the screen.
Floating edges refers to the unnatural strips which appear down the window frame of a scene where monocular images float. This is caused when the stereo window is located behind a part or all of the subject matter. Trimming or masking the outside edge of the image will remove them by bringing the window forward to the correct position.
This term is simply the use of vertical bands (printed) to surround which supplants the physical screen surround. Invented by Nigel and Raymond Spottiswoode, this floating window results in a virtual window that floats in space to eliminate the edge of screen cue conflicts, as well as extending the parallax budget of the image being projected.
Fore window image
This is an image that appears directly in front of the window frame. It is where an image cuts through the edge of the window frame, this effect is referred to as ‘floating edges’.
When related to stereography, format usually refers to an image pair’s window-frame dimension, or the method of mounting the pair of images. With 35 mm transparencies, the format is often identified thanks to the number of film-edge perforations in the width dimension of each frame. Alternatively, it can be identified by the name of the camera most commonly associated with it; e.g., 4P (also ‘Nimslo’ or ‘half-frame’); 5P (also ‘Realist’ or ‘American’); 7P (also ‘Verascope’ or ‘European’); 8P (also ‘full-frame’). Print formats are usually identified by the type of mounting; e.g., ‘traditional’ (for side-by-side pairs) or ‘ViewMagic’ (for over-and-under pairs).
This is memory that is dedicated to the systems graphics processor. This is used to store rendered pixels before they are visually displayed through the monitor.
Frame compatible 3D format
This refers to the left and right frames being or organized so they fit into a single legacy frame such as 480 x 720, 720 x 1280 or 1080 x 1920 pixels. By using spatial compression, color encoding and time sequencing the images can be pixel decimated.
Frame identification notch
A frame identification notch is something that can be found on the top or side edge of the right frame on some traditional stereo cameras. This is used as a simple way of distinguishing the right frame from the left hand frame to facilitate mounting.
Frames per second
This is the rate/speed which the systems graphic processor can render new frames, of full screens of pixels. Games use this as a way to measure a GPU’s performance. The faster GPU’s will be able to render more frames per second, which helps make the application more fluid and responsive to the users input.
Is the term used to describe the adjustment of film chips or cameras in their mounts to include or exclude the desired parts of the scene, and to set up the stereo window.
Free viewing is most commonly known to describe the fusion of the adjacent left and right images into a stereo image without needing to use any form of viewing aid. When viewing something parallel, the eyesight is forced to change from normal convergence so that the left eye will look only at the left image, and so that the right eye will look at the intended right eyes image. When using cross-eyed viewing however, the left eye will look at the right eyes intended image, and the right eye at the lefts. An advantage of cross-eyed viewing is that once the technique has been learnt, much larger and widely separated images can be fused together, although this unfortunately has the disadvantage of producing an effect known as ‘lilliputism’.
Specifically refers to the amount of times in a second that a specific event will occur. Frequency is commonly measured in Hertz (Hz) which means ‘cycles per second’.
Frozen water effect
When in a stereograph the appearance of water, particularly fast moving water (such as a waterfall) when shot with a too fast shutter speed will become more noticeable because the image will not show the same sense of movement.
Frustum effect is caused by front-to-back keystone distortion in the image space so that a cube that is parallel to the lens-base is portrayed as the frustum of a regular truncated pyramid, only with the smaller face towards the observer. In a reverse frustum distortion, the larger face will be at the front.
Full frame stereo format
This is a stereo format that uses stereo pairs of 8 perforations in every images width. This would be the same as a regular camera and is used on twin camera stereo photographs and with some specific RBT cameras. The Fed camera however can be modified to full frame.
Is the merging of the two different views of a stereo pair into one single 3D image.
Like with accidental stereo effects and multiple diplopia, fusion irregular is the fusion (combining) of points that are not homologous.
These are a series of measures to probe exactly how much stress the divergence and convergence mechanisms can cope with when they are placed under a certain amount of stress. It is linked to a person having the ability to maintain a comfortable and clear single vision whilst still keeping control of their focusing mechanism. Results from this test are difficult to analyze, however if results are low it can be expected that concentrating for long periods of time will become difficult. Adults, but in particularly children tend to show a tendency to avoid close work when their fusional reserves are low.
Ghosting is a term caused by the perception of crosstalk. Ghosting is a condition that happens when the right eye sees a part of the left eyes image, or the left eye with the rights. If this happens, ghosting will occur and will cause a very faint double image to appear on the screen.
This term is used when describing the impression of an enlarged size of an object (or objects) in a stereo image. Giantism is caused due to the use of a stereo base separation that is less than normal for the focal length of the lens. Also see hypostereo.
Graphics Processing Unit
A graphics processing unit (GPU) is a high performance three dimensional processed that can integrate the entire 3D needs. The GPU handles the rendering, lighting, setup and transformation of the 3D pipeline. It offloads all 3D calculations from the CPU, which then frees the CPU enabling it to work on other functions such as artificial intelligence and physics.
Height error (also known as vertical error)
This is an error which is present within a stereogram, and it is caused when two prints or film chips are not vertically aligned in mounting, so that the images homologous points are at various heights.
Simply stands for ‘Head Mounted Display’.
A display device worn on the user’s head. This piece of equipment is worn on the user’s head. When used with a tracking device it can create an immersive virtual reality as all background noise is blocked out.
The Holmes format is a format for stereo cards that is based upon a stereoscope that was invented by Oliver Wendall Holmes. For most antique cards this format is used and it has centered images that are further apart than the human eye (3-1/2″ x 7″). This is very significant because all viewing devices for stereo cards need to have a light bending mechanism before it reaches the eyes. The majority of viewers are prismatic and later formats for cards were not as large.
This is the name for a common type of hand-held stereoscope which has an open skeletal frame. It is named after its American physician inventor Oliver Wendell Holmes in 1859. The stereoscope has an adjustable card holder and hood to shade the eyes; it is more correctly known as a Holmes-Bates stereoscope, after Joseph Bates introduced these changes.
Also known as ‘whole drawing’ is a technique used for producing a holographic image, (an image that conveys a sense of depth, but is not a stereogram in the usual sense of providing a fixed binocular parallax). The theory of a hologram was thought up by Dr. Dennis Gabor at the Imperial College of London in 1948, however holograms were not available until the ruby laser was later invented by T.A. Mainman of Hughes Aircraft in 1960 by. Holograms in modern times are made with lasers and they produce images that make people feel that they can reach out and touch. Some holographic images appear to float in the space at the front of the frame, and their perspective changes as you move in different directions. Holograms are monochromatic, and in order to view them no specialist viewing equipment is necessary, although correct lighting is very important. In order to make a successful hologram, lengthy exposures are required with illumination by laser beams that have to be carefully set up to travel along a path with beam splitters, positioned mirrors, lenses, and specialist film.
Homologues (Homologous points)
These are identical features that are found in a stereo pairs left and right image points. The space between two homologous points is known as the separation of the two images and it can be used when determining the correct positioning of the images when mounting as a stereo pair.
Horizontal image translation
Is the horizontal moving of two image fields in order to change the value of the images parallax of corresponding points. Confusingly the term ‘convergence’ has been used to also describe this concept.
A display device that provides an image floating in mid-air in front of the user. HUD stands for ‘Head Up Display’, and it is simply a display device that provides an image floating in front of the user.
Hyperfocal distance can be described as the distance setting situated on the focusing scale of a lens mount that will help to produce a sharply focused image. It is of particular importance in stereo photography as it helps to ensure a maximum depth of field, to ensure that viewing is not confused by any out-of-focus subject matter.
This is the use of a long stereo base in order to create the effect of an enhanced stereo depth and a smaller scale of a scene. Hyperstereo creates an effect which is termed ‘Lilliputism’, due to the miniaturization of the subject which appears as a result. It is often used to help reveal depth discrimination in geological and architectural features.
By using a baseline that is smaller than the distance between the left and right eyes when taking a picture exaggerates the size of the subject which helps to make them look much larger. As a result it produces an effect called ‘Giantism’. A good use of hypostereo would be when taking a 3D photograph, as the photographer could take a picture of a small object and make it look almost life size.
An image splitter is a device placed at the front of a lens, that by using mirrors or prisms splits the image captured into to halves, which become the two images of a stereoscopic pair. The image splitter is also known as a frame splitter and a beam splitter.
Immersive is a term used when describing a system that is designed to shroud the participant in a virtual world. Visual immersion is the most common feature as it can be reached easily and effectively by using a large screen. However, the amount of immersion the user wants to feel, depends on upon many factors.
Interaxial distance and Interaxial separation
These terms refer to the distance situated between the camera lenses’ axes.
This is a type of video stream that is built up with even and odd lines or sometimes even in columns. Regular television signals such as NTSC and PAL have interlace signals which are built up of two odd and even line images which are known as fields. These fields are used to store stereoscopic left and right images which is a technique found on 3D DVDs, despite it halving the vertical resolution of the video.
Inter lens separation
Similar to base stereo, inter lens separation is the distance between the optical centers of two lenses of a stereo camera or a stereoscope.
Interocular is a term used to refer to the space between (or within) the eyes. It is the interocular distance that is situated between the eyes.
In some stereo viewers this is a provision that allows for the adjustment of the space between the lenses of the viewer to correspond with an image’s infinity separation and sometimes even the distance between the audiences eyes.
Interocular distance is the separation between the two optical centers of a twin lens stereo viewer.
Inte rocular separation
These terms refer to the distance found between the centers of the pupils when vision is at infinity. These are able to range from 55 to 75mm in adults, however the average is mainly around 65mm, which is the distance used for resolving viewer designs and calculations.
Inversion is a term used for a visual effect that can be achieved when a stereographs plane of depth are viewed in a reverse order. It is also known as ‘pseudostereo’.
An IR transmitter is a device that can send synchronization signals to wireless shutter spectacles.
JPEG stands for ‘Joint Photographic Experts Group. A JPEG is an image format that impressively reduces an images size; however it does that at the cost of removing a lot of information.’ A lot of the time, the lost information is barely noticeable. When you save an image on your computer, you can set the desired degree of compression; however this comes at the expense of image quality. The majority of the time you can get a 3:1 compression without noticing much when you save a JPEG. JPEGs use an 8×8 grid and they perform a discrete cosine transformation on every image.
JPEG 2000 is more recent and more intensive JPEG standard. The JPEG 2000 allows for a much higher compression rate in comparison to the original JPEG. It uses a wavelet transformation on the images, which uses more computer power. However, as systems are becoming faster at a rapid rate these days, this is much less of a problem now than when the first JPEG standard came out. Within a JPEG the size of the compressible area can vary, so on a positive note, no tiling pattern appears to be evident.
A JPS is a ‘stereoscopic JPEG’ file, and it is simply a stereoscopic image file format that has been based upon a JPEGs compression.
This term is used to describe a result which arises when the film plane in a projector or camera is not parallel to the screen or view. The perspective distortion that follows this produces a border to the picture which is in a trapezoidal shape, which resembles the ‘keystone’ of a masonry arch. When talking about stereo, the term is applied to the projection or capturing of two images where the cameras/projectors are toed-in so that the main objects coincide when viewed. The scenes proportions then have slight differences that produce some mismatching of the borders/outlines on both images. To produce keystoning in depth (which is more correctly known as the frustrum effect) a gross departure from the orthostereoscopic practice needs to occur when using telephoto lenses.
Lenticular is a term used by Brewster to describe his lensed stereoscope. In stereo, the term lenticular is used to describe the following; (1) a projection screen which has a surface built up of tiny silvered convex surfaces which are able to spread the reflected polarized light to increase the viewing angle. (2) A method of producing a depth effect without the need for specialist viewing equipment. It is done through using an overlay of semi-cylindrical lens-type materials which perfectly match alternating left and right images on a specially-produced print; this then enables each eye to see just one image from any viewing position, like with an autostereogram.
A lenticular screen is a projection screen that has embossed vertical lines for its finish as opposed to the emery board finish which is extremely common. However they do tend to cost more. A silvered version is essential for 3D project because any white screen will not keep the polarization of the images reflected off it.
Is the jargon term for a smaller model appearance which is a result from using a wider than normal stereo base in hyperstereography.
This is a form of polarized light. With this, the top of the electric vector belonging to the polarized light ray stays confined to its plane.
Lorgnettes are a handheld set of lenses that assists people to view stereographs
These are extremely close-up images which have been photographed with a reduced stereo base so that a correct stereo recession will be maintained.
Macro stereo photography
This is stereo photography with which the films image is around a similar or increased size of the images original size.
This term relates to computer generated optical illusions that if ‘freeviewed’ will show numerous hidden images of objects and shapes.
A mirrored stereoscope is a stereo viewer that incorporates numerous angled mirrors, similar to the Wheatstone and Cazes stereoscopes.
This refers to a condition with which one homologue is at a different height to the other. When the misalignment is rotational on both views, there is a ‘tilt’, however if it is in just one view only then there is a ‘twist’. Diplopia and eye strain are results from viewing a misaligned stereogram.
These areas are parts of a scene in a stereo image that appear in one view but not in another. They can appear to be natural if they are situated behind the stereo window, or if they are in front they will appear unnatural, just like in the case of floating edges .
Please see ‘Extrastereoscopic Cues’.
A mount when referred to in stereo usage is a specialist holder or card that is used to locate, secure and protect the two images within a stereo pair. The term usually includes any mask or framing device that may be incorporated.
Mounting is the process of attaching the left and right views to a mount or mask so that they both are correct horizontally (so the stereo view will be held in the correct place to the stereo window) and vertically (to avoid misalignment).
The mounting jig is a device used to help the mounting of stereo pairs in a correct register. It usually incorporates an alignment grid which is situated below the mount holder, and a set of viewing lenses which are above the film chips in order to enable each eye to concentrate and focus on the correct image and fuse the images.
MPEG stands for ‘Moving Picture Experts Group’. Mpegs are a type of video/audio file that can be found online. They come in three different MPEG standards which are: MPEG-1, MPEG-2, and MPEG-4.
This is the process of taking both the left and right image and then fusing them with a multiplexing software tool or alternatively with a multiplexer to create on 3D stereo image.
This is the process of fusing the two images needed for a stereoscopic display within a bandwidth.
This is the feature within a stereo images that will appear to be the nearest to the audience.
Near point of accommodation
This is the nearest point to the eyes that reading material can be read. Depending upon a person’s age the distance will vary. Usually it is measured in each eye separately, then both together, then the results are put together and a comparison is made.
Nimslo is a brand name taken from the surnames of its inventors, Jerry Nims and Allen Lo. The brand name is for a camera system that is aimed primarily to create lenticular autostereo prints by using four lenses to record the same amount of images onto 35mm film. Usually the name is used to help identify the size of mask or mount developed to hold 4-perforation-wide pairs or transparencies that are created with this camera and its derivatives.
The Nimslo format is one that uses stereo pairs of 4.5 perforations for ever images width. This is equivalent to a half frame and can be used with Nimslo and Nishika stereo cameras. With some cameras beamsplitters use a 4 perforation format, but using this would not be known as a Nimslo format.
NTSC is a interlace video stream used mainly in the United States. The NTSC is made up from 525 horizontal lines that play at a rate of 30 frames per second.
This is a simple thumb rule calculation used to determine the stereo base when you are using a non-standard camera lens separation in hyper/macro stereography. In order to achieve an optimum stereo depth, the separation of the camera lenses centers should be about one-thirtieth of the distance from the lenses that are closes to the subject in a scene. This rule works well under some optical conditions but not others, for example it works when the standard focal-length lenses are used. However, it usually needs to be varied when lenses with a longer or shorter than normal focal length are in use.
Open GL has grown to be the standard graphics API for scientific and CAD applications that are used today and it is very popular for consumer applications such as the world of PC gamin. OpenGL however, was originally created for the use on professional graphic workstations by Silicon Graphics Inc.
This is the idyllic distance and position for comfortable viewing of a stereo image.
An orthoscopic image is a stereoscopic image that is viewed with its planes of depth in a proper sequence. This is as opposed to a pseudo (or inverse) stereoscopic.
An orthostereoscopic image is an image that appears to perfectly spaced just as in the original view.
This kind of viewing is when the focal length of viewer’s lenses is equal to that of the focal length of the equipments lenses which the slides were viewed. It is said that this will allow you to view the objects as being the exact same size and with the same distance between each other within the viewer, just as in reality.
This format known as over and under involves using a mirror system in order to separate the two eyes images intended for the left and right eye that are situated on top of each other. Specialist mirror viewers are made for this over and under format.
With this over and under form of stereo recording or viewing, the left and right images are found to be positioned one above the other as opposed to side by side. They are viewed with the help of mirrors or prisms which will deflect the lights path to each eye as required.
PAL is a type of interlaced video stream that can be found in use around the world. PAL is built up from 625 horizontal lines which play at a rate of 25 frames per second.
Panoramic pictures are images that are taken of the environment around you that are captured when you rotate in a circular motion.
This is the apparent change in the position of an object when it is viewed from various points. In stereo it is often used to describe the tiny relative displacements that occur between homologues and it is more commonly and correctly defined as deviation.
Parallax budget is a range of parallax values, ranging from maximum negative up to maximum positive, within a comfortable range of viewing.
Parallax stereogram is a form of autostereogram. It describes a technique with which various thin vertical strips for each eyes views are printed in a composite form, and then they are overlaid with a lenticular sheet of cylindrical lenses. This then presents each view to the corresponding eye for viewing stereoscopically.
Parallel viewing method
This term is used to describe the viewing of a stereo image with which the left view of a stereo image is situated on the left, and the right view is found on the right. This is the usual way that stereo cards are created, unlike the technique of cross-eyed viewing.
Parallel free-vision fusion Parallel-viewing
The parallel method
This is a free viewing technique within which the lines of sight of both eyes aim and meet at a specific point which is beyond the 3D image. It works when the eyes move outwards towards the parallel lines of sight. This works well with small images, however it is kind of limited on a computer screen.
Passive polarized 3D glasses
These are 3D spectacles made with polarizing filters. They are used alongside a view screen that preserves the polarized light.
This is a technique where 3D stereoscopic imagery is achieved due to polarizing the left and right images differently, and they can be viewed using very low-cost polarizing spectacles.
These terms relate to the forming of a panorama picture which is usually made up of images taken with a fisheye lens. The images are then ‘stitched’ together in order to create a sphere or cube, with which the viewer can see all around, up, down, left and right.
Photogrammetry is a professional discipline that uses stereography as a way of map-making and scientific measuring. It is the science, art and technology of gaining reliable information about objects and the environment through measuring, recording, and interpreting photographic patterns and images of radiant electromagnetic energy and other phenomenon’s.
These terms describe an image that is contained within a two-dimensional space. However it does not necessarily appear to be flat. It could have all the depth cues apart from stereopsis.
This is a projected stereoscopic image that is made up from two planar images.
Polarization of light
The polarization of light is the dividing of beams of light into separate vectors or planes by the means of polarizing filters which were first practically applied by Edwin Land from the Polaroid Company in the 1930s. If two vectors are crossed at right angles then the vision or light rays will be obscured.
Progression (in film transport)
This is the method or amount by which the film is advanced between exposures within a purpose-built stereo camera. The Verascope progression will move by one and three frames alternately where as the Colardeau progression moves by two.
The effect that will be produced when the left and right view image are reversed. This creates a conflict between perspective image and depth.
This is the presentation of 3D images in a inverse order, so that the object furthest away will be seen as the closest and vice-versa. It is more correctly known and referred to as ‘inversion’. The effect is achieved either accidentally or deliberately when the right and lefts images are transposed for viewing.
The Pulfrich effect is named so after Carl Pulfrich who adequately described the phenomenon in 1922 in relation to a moving object, which happened to be a laterally swinging pendulum. The Pulfrich effect is a term now commonly used to refer to an illusory stereoscopic effect which occurs when 2D images moving laterally on a single plane are viewed at slightly different time intervals by each eye. The delay between the eyes is achieved by reducing the vision in just one of them. This apparent displacement that results from this is interpreted by the brain as a change in the distance of the image. A scene is then produced which gives a depth effect, the depth being proportionate to the rate of movement of the subject, not to the subjects distance.
This refers to stereo video that is taken by rolling a camera sideways at a right angle to a subject. When viewed, the viewer will need to wear glasses with one eye unobstructed and the other through a darker lens. This tricks the brain into processing frames of the video, and this results in a moving stereo image in color.
Please see beam splitter.
Random dot stereogram
This is a type of stereogram in which a three-dimensional image is created by the fusing of apparently randomly-situated dots in a stereo pair. This effect was first created manually by Herbert Mobbs in the 1920s; however it was scientifically developed with the use of computer-generated images by Bela Julesz in the 1960s. This random dot stereogram is a computer-generated image that can be perceived by binocular depth perception means only. It is a method in which a pattern is repeated at around the distance between the human eyes, which is around 2.5-2.75 inches. Minor differences in the patterns from column to column will merge to give you depth information when your eyes have diverged away from their focus point. Unfortunately this method has limitations because only graphics-type images can be shown, not a true-color image.
The realist format is the 5 perforation 35mm slide format of 23×24 which was first invented by the specification of the Stereo Realist camera. It was quickly adopted by numerous other camera manufacturers. It is a stereo format that will use stereo pairs of 5 perforations per image width. It is the most common stereo format and it is used with the TDC Coloris I and II, TDC Vivid, the Kodak and many other cameras.
Real-time 3D graphics
These are produced by a 3D graphics card. Real-time is essential if the images are needed to be interacted with, like within virtual reality, and opposed to viewing a film sequence.
This is when the images are projected out from behind a screen. One big advantage of rear projection is that the viewer cannot cast any shadows by getting in the way of the projector and screen. It is particularly important when the user is interacting with the images which are on screen. For stereoscopic rear view projection there are only certain types of rigid and flexible screens that can be used.
Please see Disparity.
This term refers to the simultaneous transmission of incompatible images from each eye.
A rig is defined as dual camera heads that are situated in a properly engineered mounting which are used to shoot stereo movies.
This term is the name which is occasionally used to delineate the 41 x 101mm, 1-5/8″ x 4″ mounts used for nearly all stereo slides. Mounts with these outer dimensions are created for the full frame formats, Realist, European and Nimslo. The term is named after the Realist Stereo Cameras inventor, Seaton Rochwite.
Rotation refers to the tilting of the images through not holding the camera horizontally, thus causing one lens to be situated higher than the other during the picture taking stage. As long as the tilting isn’t too severe it may be possible to straighten both images when mounting; however there will be a height error in part of the image.
This is a format to create 3D images or videos in which each line or row of video will alternate from top to bottom between the left and right eye.
The Savoy format is a stereo format that is produced by prisms or other forms of image-splitters on a planar camera. (over-and-under for cine images and side-by-side for still images.
This is the area appearing to be in a screen or behind the screens surface. Images that have a positive parallax will appear to be out in the screen space. The boundary between theater space and screen is known as the plane of the screen, and this area has zero parallax.
A selection device is the hardware that is used to present the correct image to the appropriate eye, and to block out the unwanted image. When watching a 3D movie the selection device is normally some form of eye wear which is used in conjunction with a device at the projector (for example a polarizing device).
This is the distance between two taking positions within a stereo photograph. The term is occasionally used to denote the space between two homologues
The term septum refers to the partition that is used in a stereo camera to separate the two image paths. The term can be applied to any partition or design element that can effectively separate the lines of sight so that only the left and right images are seen by the corresponding eye.
This is a stereo pair of images that are created using one camera that is moved by an appropriate space between the making of the left hand and right hand exposures.
Shutter glasses are a form of viewing device which should be worn on your head. They are generally double lensed and are covered in a liquid crystal material and controlled by your computer. When you are viewing a 3D image using these spectacles your computer will display the left image first. The computer will instruct your glasses to open the left eye’s “shutter”, which then makes the liquid crystal transparent, and then the computer will close the right eye’s “shutter” which then makes the liquid crystal opaque. Then within a short interval of 1/30 or 1/60 of a second, the right image is displayed, and then the glasses are simply instructed to reverse the shutters. This process will keep on going for as long as you are viewing the image. As the time interval is so short, your brain isn’t able to tell the difference in time, and so it views them simultaneously.
This term is used as a verb, and it means to assemble a stereo camera from any relevant parts of two similar planar cameras.
A silvered screen is a type of screen surface that is used for passive stereoscopic frontal projection. These silvered screens maintain the polarization of the light rays introduced to it through polarizing filters in front of the two projector lenses.
Single image random dot stereogram
This was popularized thanks to the “Magic Eye” type books of the 1990s. It refers to a computer generated stereogram within which the depth information is merged into a single image. It is a form of random dot stereogram in which the stereo pair is encoded into one single composite image that each eye must to interpret separately. In 1979 the first ever single image random dot stereogram was programmed on an Apple II computer by Christopher Tyler and Maureen Clarke.
A slide bar is a device that is used for taking sequential stereo pairs of non-moving subjects, which enables a planar camera to move by an adequate separation whilst keeping the camera in a correct horizontal register with the optical axes that are either parallel or “toed-in” to make a convenient stereo window.
Spinography is done by moving around a subject and taking pictures at an interval of every 10-20degrees. Or simply by placing the camera on a tripod and the subject on a turntable and rotating it the same amount of degrees between capturing the shot. This can also be done using 3D modeling software; however this does not create the same sense of depth as stereographics. In order to view spinography on a computer you will normally need to download a small program for your browser, which is known as a ‘plug in’.
Is the opposite effect to ‘stretch’. Squeeze is an effect which happens when a stereogram is viewed from a distance closer than the optimum, particularly in projection. It is the diminution of depth within a stereogram in relation to its other two dimensions.
Stereo blind is a term which is commonly used to describe people that cannot fuse two images into one with depth.
This is the furthest distance at which spatial depth effects are usually discernible. They are usually regarded at 200 meters for practical purposes.
Charles Wheatstone in 1838 created the first ever stereoscopic viewer for the 3D viewing of stereopairs.
Stereoscopic vision Stereopsis
A two eye view will merge in the brain which then creates the visual appearance of one 3D image. This is a byproduct of good binocular vision skills.
This is the viewing frame or border of a stereo pair, that defines a spatial plane through which 3D image can be viewed beyond. It is a design feature in some stereo cameras, where the lenses axes are slightly offset (inwards) from the axes of the film apertures. It creates a self-determining window in the resulting images, which is normally set at around a 2 meters distance away from the audience. If any of the objects appear to be nearer to the viewer than the plane then it is known as ‘breaking the window’.
This is a stereoscopic instrument which is used for measuring parallax. It usually includes the task of measuring photograph coordinates of the images points.
Stereogram is the general term for any arrangement of left and right hand views which produce a 3D outcome. The result may consist of one of the following things. (1) A over and under or side-by-side pair of images (2) Superimposed images which are projected onto a screen (3) In video, alternate projected left and right images which fuse through the persistence of vision. (4) A vectograph (5) Lenticular images (6) A color-coded composite (anaglyph)
This term created by Wheatstone refers to a three dimensional image which is produced by drawing. It now denotes any image that is viewed from a stereogram.
Is the term used for a person who makes stereo pictures.
This is an early style of stereoscope that carries a large monocular lens which is situated above the two regular stereoscopic lenses, and it is used for the viewing of planar photographs.
These are two images which are made from different points of view that are placed side by side. When they are viewed with the correct equipment the effect is remarkably life like.
Stereography is the practice and art of 3D image making.
Stereojet prints are made from a special transparency material which has polarized images ink jetted onto either side. They can be shown as transparencies or mounted against a reflective surface and scaled up to poster size. They can be viewed with a cheap pair of polarized lenses which are made specifically for stereo viewing. Regular polarized sunglasses tend not to work as their lenses are mounted at the wrong polarization angle. The colors are truer than those in anaglyphs and when they are properly lit the outcome looks extremely real.
This is based upon the idea of stereo viewing which comes from the fact that humans naturally view their surroundings in three dimensions. Each eye can see a single scene from slightly different position. Our brain the works out the difference between them and reports/shows it in the third dimension.
Stereoplexing which is also known as stereoscopic multiplexing is a way to incorporate information for the left and right eyes perspective views into one single information channels without an expansion of the bandwidth.
This instrument is used for plotting a map or obtaining spatial solutions through observing pairs of stereo photographs.
Is the mixing (blending) of stereopairs by the human brain. It is the mental process of converting left and right eye images seen into the awareness of depth in a single 3D concept.
Stereopicon is a term which is used when describing a stereoscope. The term was first used in 1875 when identifying a twin image magic lantern which could be used to get information on depth by the blended sequenced presentation of a collection of planar views of a subject. It was later erroneously applied to other kinds of non-stereo projectors.
This is a process that uses 2D information which is held in a pair of images to recreate an objects position and shape.
A stereoscope is a binocular optical instrument which helps a viewer obtain a mental impression of a 3D model when viewing stereograms. The stereoscope device uses and designs of other stereoscopic instruments include a combination of lenses, prisms and mirrors. It is normally an optical device which has a twin viewing system.
Sterescopic images are ‘solid looking’ images. They have visible depth as well as showing height and width. The can refer to any device or experience that is associated with binocular depth perception.
3D Stereoscopic is two images which were captured from slightly different angles, which makes them appear three dimensional when they are viewed together.
Stereoscopy is the science and art of making images with the depth sense stereopsis. Stereography is the reproduction of the effect of binocular vision due to the other graphic or photographic means.
The term stretch refers to the elongation of depth within a stereogram in relation to its other two dimensions. It is usually caused when the stereogram is viewed from more than the optimum distance, especially when in projection. Stretch is the direct opposite to the effect defined as ‘squeeze’,
Strip of stereo photographs
This is a collection/series of overlapping photographs which were taken at regular intervals to create a sequence of stereo images whilst the camera was being moved in one direction.
The surround is simply the horizontal and vertical edges that are directly adjacent to the screen.
Within stereoscopy, the term T is used to denote the distance between the human eyes, which are known as the interpupilary or inte rocular distance. TC however is used to denote the space between a stereoscopic cameras head lenses axes and is known as the interaxial.
This is a stereoscopic image that shows the original scene to the audience exactly as it would have been seen in reality; i.e., with the same positions of scenic elements, apparent scale and a stereo magnification of x1 for each subject in the viewer.
The taxiphote viewer is a form of cabinet that was created for viewing a collection of stereograms in sequence.
Is a camera that uses the Nimslo format; however it has been modified by Technical Enterprises so it only exposes two frames per exposure as opposed to the quadruple exposure needed for lenticular processing.
This relates to the area that appears to be in front of the screen or out into the audience. It can also be known as ‘audience space’. Images that have a negative parallax will appear like they are in the theater space. However, the boundary between the screen and theater space is the plane of the screen and has zero parallax.
Therapeutic 3D viewing
Therapeutic 3D viewing is the use of 3D material to improve visual skills such as; depth perception, binocular coordination and eye teaming.
When described in stereo usage it is an early type of stereogram on translucent paper within a card frame. It is usually tinted and has been known to have pin-pricked highlights designed for viewing with backlighting.
Toeing-in is the technique of causing the optical axes of twin planar cameras to converge at a distance point that is the same to that of a desired stereo window.
Virtual reality environments use a 3D tracking system in order to track the user’s body movement. There are numerous types, such as; magnetic, optical and ultrasonic tracking systems.
Simply put, this is the use of film photography with analytical or analogue stereoplotters.
Transcoding is the process of converting one 3D video file into another format. For example; converting a field sequential 3D video into a column interleaved image data file.
This is the changing over of the inverted images that are produced from a stereo camera to the correct vertical, left and right presentation which is required for normal viewing. This can be achieved optically by a transposing camera or viewer, and mechanically through the means of a specialist printing frame. A manual option is also available and can be done during the mounting of the images.
Tru-Vue is the propriety name of a commercial stereo transparency viewing system which shows a series of views in a film strip sequence on a single card mount.
Twin camera stereo photography
This kind of stereo photography uses two monoscopic cameras which normally have shutters and other various components connected externally or internally to them by electronic or mechanical means. An advantage of this style of photography is that it uses common formats (e.g. medium format and full frame). It is also able to achieve a variable stereo base. However some drawbacks include difficulty with matching cameras, film and getting a normal stereo base. To achieve more consistent results camera bars can be used.
Twist is a rotational displacement/movement of one view in a stereo pair in relation to the other image.
A vectograph is a form of polarization-coded stereograms which were originally created by the Polaroid company. The images in a vectograph are mounted at the front and rear of a transparent base, and are then viewed by using polarized light or by using polarized filters. It is the polarized version of an anaglyph stereograph.
Please see ‘Progression format’.
View Magic is the name of a commercial stereo print viewing system which uses angled mirrors, similar to that of a periscope. It is used for over and under mounted prints, and it is now the name being used to identify this mounting format.
This is the proprietary name of a stereo transparency image display and viewing system that uses seven stereo pairs mounted in a circular rotating holder, and they are viewed with a specifically made stereo viewer.
View-Master personal format
This format is used with a ‘Viewmaster personal camera’. It produces two rows of chips which are about 18x10mm per roll of 35mm film. They were used with a cutter to make view master reels for personal use. This however is not the same method that is used today for the mass marketed reels manufactured by Fisher Price.
Virtual Reality or VR is a system of computer generated three dimensional images viewed with a headset which is linked to the computer in use, and it incorporates left and right eye electronic displays. The controlling software will allow the user to interact with the environment by allowing them to move and to see the 360° scene surrounding them. It also allows the user to grasp virtual objects in the environment through the technology of an electronically linked hand set. Despite the environment letting you see all sides of an object by moving and rotating it, you actually are only seeing dimensions at one time.
Vision can be defined as the act of interpreting and perceiving visual information.
VRML stands for ‘Virtual Reality Markup Language’. VRML are a set of standards for spinography software. Images are not really found to be VR.
The Wheatstone stereoscope was named after its inventor Sir Charles Wheatstone who devised the earliest type of stereoscope in 1832, which was prior to the advent of photography. It is a reflecting mirrored stereoscope in which a set of images (which need to be reversed) are placed facing each other at both ends of a horizontal bar and then they are viewed through a set of angled mirrors which are attached midway between them both.
A stereo window refers to the screen surround unless floating windows are being used.
Refers to the area of the graphical memory used to store the Z, or depth information about objects being rendered. The Z-buffer uses the value of a pixel to determine whether to place it in front or behind another pixel. Z-buffers calculations help to prevent any background objects from replacing/overwriting any objects that are in the foreground of the frame buffer.
ZPS stands for ‘Zero parallax setting’. The ZPS means to control the screens parallax in order to place an object in the plane of the screen. Prior terminology says that left and right images are converged when in the plane of the screen.
List compiled from a variety of sources, including: Lenny Lipton, Art Berman, Insight Media