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Accommodation . Focusing of the eyes. Accommodation/Convergence Relationship . The habitual relationship established between the focusing and converging of the eyes when looking at an object in the visual world. Binocular . Two eyes. The term "binocular stereopsis" is used in some psychology books for the depth sense simply described as "stereopsis." Conjugate Points . See Corresponding Points . Convergence . The rotation of the eyes, in the horizontal direction, producing fusion. The term has also been used to describe the movement of left and right image fields or the "toe-in" or rotation of camera heads. Corresponding Points . The image points of the left and right fields referring to the same point on the object. The distance between the corresponding points is defined as parallax . Crosstalk . Incomplete isolation of the left and right image channels. Crosstalk is a physical entity, whereas ghosting is a psychophysical entity. CRT Space . The region appearing to be within a CRT display screen or behind the surface of the screen. Images with negative parallax will appear to be in CRT space. Depth Range . A term that applies most appropriately to stereoscopic images created with cameras. It is the distance from the ZPS point to the background point having parallax which is acceptable in terms of ease of viewing. Disparity . The distance between conjugate points on overlaid retinae, sometimes called retinal disparity . The corresponding term for the display screen is parallax . Extrastereoscopic Cues . Those depth cues appreciated by a person using only one eye. Also called monocular cues . Field-Sequential . In the context of electro-stereoscopy, the rapid alternation of left and right perspective viewpoints as fields are written on the video display screen. Fusion . The combination, by the mind, of the left and right images - seen by the left and right eyes - into a single image. Ghosting . The perception of crosstalk is called ghosting . HIT . Horizontal image translation. The horizontal shifting of the two image fields to change the value of the parallax of corresponding points. The term convergence has been used to denote this concept. Homologous Points . See Corresponding Points . Infrared (IR). Invisible radiation used as the communications link for CrystalEyes . Interaxial Distance . Also interaxial separation . The distance between camera lenses' axes. See t . Interocular Distance . See Interpupillary Distance . Interpupillary Distance . Also interpupillary or interocular separation . The distance between the eyes' axes. See t . Monocular Cues . See Extrastereoscopic Cues . Multiplexing . The technique for placing the two images required for an electro-stereoscopic display within an existing bandwidth. Parallax . The distance between conjugate points. It may be measured with a ruler or, given the distance of an observer from the screen, in terms of angular measure. In the latter case, the parallax angle directly provides information about disparity. Planar . Flat. Two-dimensional. A planar image is one contained in a two-dimensional space, but not necessarily one which appears flat. It may have all the depth cues except stereopsis. Plano-Stereoscopic . A stereoscopic display which is made up of two planar images. Retinal Disparity . See Disparity . Selection Device . The hardware used to present the appropriate image to the appropriate eye and to block the unwanted image. Side-by-Side . The format used by StereoGraphics' video system to squeeze left and right images into a single video field. Stereo . Short for stereoscopic . I've limited its usage because the term is also used to denote stereophonic audio. Stereoplexing . Stereoscopic multiplexing. A means to incorporate information for the left and right perspective views into a single information channel without expansion of the bandwidth. Stereopsis . The binocular depth sense. Literally, "solid seeing." Stereoscope . A device for viewing plano-stereoscopic images. It is usually an optical device with twin viewing systems. Stereoscopy . The art and science of creating images with the depth sense stereopsis . Surround . The vertical and horizontal edges of the screen immediately adjacent to the display. t . In stereoscopy, t is used to denote the distance between the eyes, called the interpupillary or interocular distance. tc is used to denote the distance between stereoscopic camera heads' lens axes. Viewer Space . The region between the display screen surface and the viewer. Images will appear in this region if they have negative parallax. White Line Code . The last line of the video signal used to tag left and right perspectives and trigger the SimulEyes VR eyewear shutters to sync with the fields. Window . The stereo window corresponds to the screen surround given the algorithms described in these pages. ZPS . Zero parallax setting. The means used to control screen parallax to place an object, or a portion of an object or picture, in the plane of the screen. ZPS may be controlled by HIT. When image points have ZPS, prior terminology would say that they were "converged." That term is not used here in that sense, because it may be confused with the convergence of the eyes, and because the word implies rotation of camera heads or a software algorithm employing rotation. Such rotation invariably produces geometric distortion. |
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