Tutorial: 3D Dictionary

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This shooting technique allows the production of two images or films of the same scene simultaneously but from two different angles.
In other words, each camera imitates the angle of vision of each eye.
The distance between the lenses and the angle of convergence determines the sense of depth.

Are pictures or films seen in 3D by means of glasses with coloured lenses.
The usual colours are red (left lens) and cyan (blue+green, right lens) but other colour combinations are possible such as Yellow/Blue, Green/Magenta.

Title	Description
Stereo or Stereoscopic	Images or films which, when viewed with the appropriate means (such as glasses) or methods (cross-eyed or parallel viewing) create a true three-dimensional image. Lenticular images are also considered stereos.
Hyperstereo and Hypostereo	Hyperstereo is an exaggerated 3D effect obtained by widening the stereo base of the image pair, which makes objects in the image appear smaller. Hypostereo is the exact opposite: by narrowing the stereo base,
Keystone stereo	This shooting technique allows the production of two images or films of the same scene simultaneously but from two different angles. In other words, each camera imitates the angle of vision of each eye. The distance between the lenses and the angle of convergence determines the sense of depth.
Anaglyphs	Are pictures or films seen in 3D by means of glasses with coloured lenses. The usual colours are red (left lens) and cyan (blue+green, right lens) but other colour combinations are possible such as Yellow/Blue, Green/Magenta.
Cha cha	"Cha Cha" is a method of taking stereo images with a single camera by taking one picture, shifting the camera laterally and taking the second picture of the stereo pair. The technique requires great coordination and precludes moving subjects, but there are many photographers who take very high quality stereo images using this technique.
Beam Splitter	The beam splitter is an optical device that attached to the lens of a single camera in order to produce a stereo pair. Its function is very simple, allowing the scene to be projected onto the film or imaging device from two different angles. The resulting images are distributed in equal parts onto the same frame. Ordinary beam splitters normally do not produce high-quality stereo pairs for many reasons, including the fixed angle of the lenses. There are beam splitters available for every type and brand of camera.
Shift	In general, this term is used to define the change in colour of anaglyphs, or the lateral displacement either in pixels or percentages. For example, in traditional anaglyphs, the colour red is usually shifted via software in order to obtain an optimal three-dimensional effect. The amount of lateral shift affects the range of compatible viewers; exaggerated lateral shifts are only viewable by a reduced percentage of viewers.
Ghost or Ghosting	A condition that occurs when the right eye sees a portion of the left image or vice versa causing a faint but persistent double image to appear. Ghosts can be caused by exaggerated shifts and other causes.
Stereo Pairs	A set of two images or films, one left and one right.
Optic Rivalry	A problem endemic to all stereophotography, including anaglyphs. The rivalry occurs when graphic images are visible in one half of the stereo pair and not the other. The principal cause for an object being hidden in one of the pictures or films is a different angle, but there are other causes as well such as poor alignment of the taking lenses, varying exposures, reflections, etc.
Window Violation	Often abbreviated as "WV" indicates that the stereo image has a three dimensional effect that is exaggerated and unnatural whereby an object protrudes beyond the "window" frame of the image.
Conversion from 2D to 3D	Often abbreviated as 2D>3D is a graphic procedure to transform a two-dimesional image into a stereo image.
Anaglyphoscope	The technical term for "a pair of spectacles for viewing an anaglyph."
Side by Side	Placement of two images next to one another for viewing with a stereoscope or freeviewing (cross-eyed or parallel). The position of the two images and the space between them determines the amount of depth and the 3D effect. In addition to stereo viewing, the side by side positioning makes it possible to correct alignment, rotational errors, and non parallelism.
Stereoscope	Optical device for viewing side by side stereo pairs. Viewing both images simultaneously through a stereoscope produces a single three-dimensional image. There are various types of stereoscopes distinguished by their method of reflection (prisms, mirrors, direct views) and by their quality.
Cross/Parallel Eye "Freeviewing"	A common method for viewing side by side images without the aid of an intermediate device. The technique consists of viewing the images and converging one's eyes until the separate images fuse into a single stereo image. Cross-eyed viewing is easier to learn compared to parallel viewing which is more unnatural but has the advantage of rendering a better illusion of depth. There are viewers available that help the eyes to converge at the correct angle.
Lenticular prints	This process is in continual and rapid expansion and there are many types of support available for both print applications and computer monitors. Lenticular images are made up from a series of lenses close together. The lenses are curved and focused in such a manner that each eye is able to view only part of the image taken by each lens. In other words, the left eye sees only the left image and vice versa. Obviously, the perspective of the viewer must be fixed because altering either one's position or moving the image changes the view. Although a shortcoming in terms of stereo vision, lenticulars allow the creation of other effects and animation.
Polarized Projection	This method of stereo viewing requires the use of specialized screens which maintain the polarization of light projected from two different sources. There are three fundamental elements to polarized projection: 1) two projection lenses, each with polarizing filters at perpendicular angles to one another 2) a screen that maintains the polarization (usually silver), and 3) glasses with polarized lenses oriented to match the projection filters. In this manner, the left eye views on the left image and vice versa.
Frame	In stereo works, this term unfortunately has two meanings: a single image from a film or a border. For exmple, 3D Gugle includes a function for creating and adding borders, and many options for manipulating the frames of a film.
Layer	A layer is a new image created by lifting a discrete and complete portion from another image such as a single flower lifted from a picture of a bouquet. A layer can also be a graphic object that belongs to a definite depth of field such as the mountains in the background of a panorama. Layers are new images with many properties, including the ability to be superimposed.
Depth Map	The depth map is a map that includes depth information for every single pixel. There are two principal types of depth map, "hidden" made up of numerical values, and "image" which can be viewed and show depth values in a grey scale. In "image" depth maps, the near areas and objects are brightest. Depth maps have many uses, be they for conversion into 3D or for the manufacture of tangible objects with pantographs or machines operated by numerical control.
RGB and CMYK	Colours can be represented by different mathematical models and unfortunately it is not always possible to convert from one to another without losing graphic information. Montors work with the Red, Green, Blue or "RGB" whereas printer run on Cyan, Magenta, Yellow, Black ("CMYK"). These differences create problems when printing anaglyphs, in particular when transformation errors alter red registers. 3D Gugle has a feature, Luminance, that compensates for converion errors between the models, in addition to other useful colour management functions.
JPEG	The JPEG format for compressing images is one of the important ideas that has helped foster the development of digital and internet graphics. The JPEG format is indispensible for publishing your work on the web, but when working with stereo images, it is necessary to pay close attention to compression issues in order to avoid undesired effects. When saving a stereo image as a jpeg, in addition to the compression, it is vital to use the right sub-sampling criteria. 3D Gugle inludes a specific option, "Set JPEG Compression" to analyze the results and select the correct parameters.
PNG	The PNG format compresses images without altering grahic information as JPEG compression does. Images compressed with PNG, however, do not reduce file sizes as much as JPEG compression. PNG can be used over the internet, but it main value is for archiving files.
Alpha Blend	Alpha Blend is a graphic process which is able to blend two superimposed images. Generally, the percentages of the original images can be shifted with certain keys, pg up and pg dn in 3D Gugle. The purpose is to create a transparent effect.
Trasparence	The trasparence process, not to be confused with Alpha Blend, makes only a specific colour transparent. When two images are superimposed and a transparent colour us established, the resulting image will include the upper image with the chosen transparent colour underneath.