Stereoscopy (also called stereoscopic or 3-D imaging) is any technique capable of recording three-dimensional visual information or creating the illusion of depth Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes' different positions in in an image.
Human vision uses several cues to determine relative depths in a perceived scene[1]. Some of these cues are:
- Stereopsis Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes' different positions in
- Accommodation of the eyeball Accommodation is the process by which the vertebrate eye changes optical power to maintain a clear image on an object as its distance changes (eyeball focus)
- Occlusion of one object by another
- Subtended visual angle of an object of known size
- Linear perspective (convergence of parallel edges)
- Vertical position (objects higher in the scene generally tend to be perceived as further away)
- Haze, desaturation, and a shift to bluishness
- Change in size of textured pattern detail
All the above cues, with the exception of the first two, are present in traditional two-dimensional images such as paintings, photographs, and television. Stereoscopy is the enhancement of the illusion of depth in a photograph A photograph is an image created by light falling on a light-sensitive surface, usually photographic film or an electronic imager such as a CCD or a CMOS chip. Most photographs are created using a camera, which uses a lens to focus the scene's visible wavelengths of light into a reproduction of what the human eye would see. The process and, movie A film, also called a movie or motion picture, is a story conveyed with moving images. It is produced by recording photographic images with cameras, or by creating images using animation techniques or visual effects. The process of filmmaking has developed into an art form and industry, or other two-dimensional image by presenting a slightly different image to each eye Eyes are organs that detect light, and convert it to electro-chemical impulses in neurons. The simplest photoreceptors in conscious vision connect light to movement. In higher organisms complex neural pathways exist that connect the eye, via the optic nerve to the visual cortex and other areas of the brain. Complex optical systems with resolving, and thereby adding the first of these cues (stereopsis Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes' different positions in) as well. It is important to note that the second cue is still not satisfied and therefore the illusion of depth is incomplete.
Many 3D displays use this method to convey images. It was first invented by Sir Charles Wheatstone Sir Charles Wheatstone FRS , was a British scientist and inventor of many scientific breakthroughs of the Victorian era, including the English concertina, the stereoscope (a device for displaying three-dimensional images), and the Playfair cipher (an encryption technique). However, Wheatstone is best known for his contributions in the development in 1838.[2] Stereoscopy is used in photogrammetry Photogrammetry is the practice of determining the geometric properties of objects from photographic images. Photogrammetry is as old as modern photography and can be dated to the mid-nineteenth century and also for entertainment through the production of stereograms A stereogram is an optical illusion of depth created from flat, two-dimensional image or images. Originally, stereogram referred to a pair of stereo images which could be viewed using stereoscope. Other types of stereograms include anaglyphs and autostereograms. Stereoscopy is useful in viewing images rendered from large multi-dimensional In mathematics and physics, the dimension of a space or object is informally defined as the minimum number of coordinates needed to specify each point within it. Thus a line has a dimension of one because only one coordinate is needed to specify a point on it. A surface such as a plane or the surface of a cylinder or sphere has a dimension of two data sets such as are produced by experimental data. Modern industrial three dimensional photography may use 3D scanners A 3D scanner is a device that analyzes a real-world object or environment to collect data on its shape and possibly its appearance . The collected data can then be used to construct digital, three dimensional models useful for a wide variety of applications. These devices are used extensively by the entertainment industry in the production of to detect and record 3 dimensional information.[3] The three-dimensional depth information can be reconstructed from two images using a computer by corresponding the pixels in the left and right images. Solving the Correspondence problem Given two or more images of the same 3D scene, taken from different points of view, the correspondence problem is to find a set of points in one image which can be identified as the same points in another image. A human can normally solve this problem quickly and easily, even when the images contain significant amount of noise. In computer vision in the field of Computer Vision Computer vision is the science and technology of machines that see, where see in this case means that the machine is able to extract information from an image that is necessary to solve some task. As a scientific discipline, computer vision is concerned with the theory behind artificial systems that extract information from images. The image data aims to create meaningful depth information from two images.
Traditional stereoscopic photography consists of creating a 3-D illusion starting from a pair of 2-D images. The easiest way to enhance depth perception Depth perception arises from a variety of depth cues. These are typically classified into binocular cues that require input from both eyes and monocular cues that require the input from just one eye. Binocular cues include stereopsis, yielding depth from binocular vision through exploitation of parallax. Monocular cues include size: distant in the brain is to provide the eyes of the viewer with two different images, representing two perspectives Perspective, in context of vision and visual perception, is the way in which objects appear to the eye based on their spatial attributes; or their dimensions and the position of the eye relative to the objects. There are two main meanings of the term: linear perspective and aerial perspective of the same object, with a minor deviation exactly equal to the perspectives that both eyes naturally receive in binocular vision Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a wider field of view. For example, a human has a. If eyestrain and distortion are to be avoided, each of the two 2-D images preferably should be presented to each eye of the viewer so that any object at infinite distance seen by the viewer should be perceived by that eye while it is oriented straight ahead, the viewer's eyes being neither crossed nor diverging. When the picture contains no object at infinite distance, such as a horizon or a cloud, the pictures should be spaced correspondingly closer together.
Contents
|
Etymology
The word stereoscopy derives from the Greek Greek , an independent branch of the Indo-European family of languages, is the language of the Greeks. Native to the southern Balkans, it has the longest documented history of any Indo-European language, spanning 34 centuries of written records. In its ancient form, it is the language of classical ancient Greek literature and the New Testament of "στερεός" (stereos), "firm, solid"[4] + "σκοπέω" (skopeō), "to look", "to see".[5]
Visual requirements
Anatomically, there are 3 levels of binocular vision Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a wider field of view. For example, a human has a required to view stereo images:
- 1 Simultaneous perception
- 2 Fusion (binocular 'single' vision)
- 3 Stereopsis Stereopsis is the process in visual perception leading to the sensation of depth from the two slightly different projections of the world onto the retinas of the two eyes. The differences in the two retinal images are called horizontal disparity, retinal disparity, or binocular disparity. The differences arise from the eyes' different positions in
These functions develop in early childhood. Some people who have strabismus Strabismus is a condition in which the eyes are not properly aligned with each other. It typically involves a lack of coordination between the extraocular muscles that prevents bringing the gaze of each eye to the same point in space and preventing proper binocular vision, which may adversely affect depth perception. Strabismus can be either a disrupt the development of stereopsis, however orthoptics Orthoptics (from the Greek words ortho meaning "straight", and optikas meaning "vision" is a discipline dealing with the diagnosis and treatment of defective eye movement and coordination , binocular vision, and amblyopia by eye care professionals.. There are five areas of treatment for orthoptic problems: treatment can be used to improve binocular vision Binocular vision is vision in which both eyes are used together. The word binocular comes from two Latin roots, bini for double, and oculus for eye. Having two eyes confers at least four advantages over having one. First, it gives a creature a spare eye in case one is damaged. Second, it gives a wider field of view. For example, a human has a. A person's stereoacuity determines the minimum image disparity they can perceive as depth.
Side-by-side (non-shared viewing scenarios)
Characteristics
Stereograph published in 1900 by North-Western View Co. of Baraboo, Wisconsin Baraboo is the largest city in and the county seat of Sauk County, Wisconsin, located along the Baraboo River. Its 2007 estimated population was 11,550.[citation needed], digitally restored.Little or no additional image processing is required. Under some circumstances, such as when a pair of images is presented for crossed or diverged eye viewing, no device or additional optical equipment is needed.
The principal advantages of side-by-side viewers is that there is no diminution of brightness so images may be presented at very high resolution and in full spectrum color. The ghosting associated with polarized projection or when color filtering is used is totally eliminated. The images are discretely presented to the eyes and visual center of the brain, with no co-mingling of the views. The recent advent of flat screens and "software stereoscopes" has made larger 3D digital images practical in this side by side mode, which hitherto had been used mainly with paired photos in print form.[citation needed]
Freeviewing
Freeviewing is viewing a side-by-side image without using a viewer.[6]
| Wikimedia Commons has media related to: Parallel-view stereo images |
- The parallel view method uses two images not more than 65mm between corresponding image points; this is the average distance between the two eyes. The viewer looks through the image while keeping the vision parallel; this can be difficult with normal vision since eye focus and binocular convergence normally work together.
| Wikimedia Commons has media related to: Crosseye-view stereo images |
- The cross-eyed view method uses the right and left images exchanged and views the images cross-eyed with the right eye viewing the left image and vice-versa. Prismatic, self masking glasses are now being used by cross-view advocates. These reduce the degree of convergence and allow large images to be displayed.
Several methods are available to freeview.[7][8]
Stereographic cards and the stereoscope
Two separate images are printed side-by-side. When viewed without a stereoscopic viewer the user is required to force his eyes either to cross, or to diverge, so that the two images appear to be three. Then as each eye sees a different image, the effect of depth is achieved in the central image of the three.
The stereoscope offers several advantages:
- Using positive curvature (magnifying) lenses, the focus point of the image is changed from its short distance (about 30 to 40 cm) to a virtual distance at infinity. This allows the focus of the eyes to be consistent with the parallel lines of sight, greatly reducing eye strain.
- The card image is magnified, offering a wider field of view and the ability to examine the detail of the photograph.
- The viewer provides a partition between the images, avoiding a potential distraction to the user.
Stereograms cards are frequently used by orthoptists Orthoptics (from the Greek words ortho meaning "straight", and optikas meaning "vision" is a discipline dealing with the diagnosis and treatment of defective eye movement and coordination , binocular vision, and amblyopia by eye care professionals.. There are five areas of treatment for orthoptic problems: and vision therapists in the treatment of many binocular vision and accommodative The accommodation reflex is a reflex action of the eye, in response to focusing on a near object, then looking at distant object , comprising coordinated changes in vergence, lens shape and pupil size. It is dependent on cranial nerve II (afferent limb of reflex), higher centres and cranial nerve III disorders.
|
Vintage Stereoscopic Picture (for parallel viewing) |
Vintage Stereoscopic Picture (for cross viewing) |
Narrow paired images (for cross viewing) |
Stereoscopic Picture of Piano Keys (for cross viewing) |
Transparency viewers
Stereoscope and case – during WWII this tool was used by Allied photo interpreters to analyze images shot from aerial photo reconnaissance platforms.The practice of viewing transparencies in stereo via a viewer dates to at least as early as 1931, when Tru-Vue began to market filmstrips that were fed through a handheld device made from Bakelite Bakelite , or polyoxybenzylmethylenglycolanhydride, is an early plastic. It is a thermosetting phenol formaldehyde resin, formed from an elimination reaction of phenol with formaldehyde, usually with a wood flour filler. It was developed in 1907–1909 by Belgian chemist Dr. Leo Baekeland. In the 1940s, a modified and miniaturized variation of this technology was introduced as the View-Master. Pairs of stereo views are printed on translucent film which is then mounted around the edge of a cardboard disk, images of each pair being diametrically opposite. A lever is used to move the disk so as to present the next image pair. A series of seven views can thus be seen on each card when it was inserted into the View-Master viewer. These viewers were available in many forms both non-lighted and self-lighted and may still be found today. One type of material presented is children's fairy tale Fairy tale is an English language term for a type of short narrative corresponding to the French phrase conte de fée, the German term Märchen, the Italian fiaba, the Polish baśń or the Swedish saga. Only a small number of the stories thus designated explicitly refer to fairies. Nonetheless, the stories may be distinguished from other folk story scenes or brief stories using popular cartoon The word cartoon has various meanings, based on several very different forms of visual art and illustration. The artists who draw cartoons are known as cartoonists characters. These use photographs of three dimensional model sets and characters. Another type of material is a series of scenic views associated with some tourist destination, typically sold at gift shops located at the attraction.
Another important development in the late 1940s was the introduction of the Stereo Realist camera and viewer system. Using color slide film, this equipment made stereo photography available to the masses and caused a surge in its popularity. The Stereo Realist and competing products can still be found (in estate sales and elsewhere) and utilized today.
Low-cost folding cardboard viewers with plastic lenses have been used to view images from a sliding card and have been used by computer technical groups as part of annual convention proceedings. These have been supplanted by the DVD DVD, also known as Digital Video Disc or Digital Versatile Disc, is an optical disc storage media format, and was invented and developed by Philips, Sony, Toshiba, and Time Warner in 1995. Its main uses are video and data storage. DVDs are of the same dimensions as compact discs , but are capable of storing just under seven times as much data recording and display on a television Television is a widely used telecommunication medium for transmitting and receiving moving images, either monochromatic ("black and white") or color, usually accompanied by sound. "Television" may also refer specifically to a television set, television programming or television transmission. The word is derived from mixed Latin set. By exhibiting moving images of rotating objects a three dimensional effect is obtained through other than stereoscopic means.
An advantage offered by transparency viewing is that a wider field of view may be presented since images, being illuminated from the rear, may be placed much closer to the lenses. Note that with simple viewers the images are limited in size as they must be adjacent and so the field of view is determined by the distance between each lens and its corresponding image.
Good quality wide angle lenses are quite expensive and they are not found in most stereo viewers.
|
Sat, 19 Jun 2010 03:21:43 GMT+00:00
San Francisco Chronicle 3-D imagery, or stereoscopy , has been around in various forms for a long time. The basic idea remains simple: Use two cameras to take the same picture from ...
Christopher Stewart
Fri, 21 Aug 2009 12:12:18 GM
Stereoscopy. is the definitive title of a song which I used to refer to as Point Of View. I changed my mind about the title while writing and singing the melodies, thinking that the word doesn t get the chance to be employed very ...
