Visual angle
Visual Vis"u*al, a. [L. visualis, from visus a seeing, sight: cf. F. visuel. See {Vision}.] 1. Of or pertaining to sight; used in sight; serving as the instrument of seeing; as, the visual nerve. [1913 Webster]

The air, Nowhere so clear, sharpened his visual ray. --Milton. [1913 Webster]

2. That can be seen; visible. [R.] [1913 Webster]

{Visual angle}. (Opt.) See under {Angle}.

{Visual cone} (Persp.), a cone whose vertex is at the point of sight, or the eye.

{Visual plane}, any plane passing through the point of sight.

{Visual point}, the point at which the visual rays unite; the position of the eye.

{Visual purple} (Physiol.), a photochemical substance, of a purplish red color, contained in the retina of human eyes and in the eyes of most animals. It is quickly bleached by light, passing through the colors, red, orange, and yellow, and then disappearing. Also called {rhodopsin}, and {vision purple}. See {Optography}.

{Visual ray}, a line from the eye, or point of sight.

{Visual white} (Physiol.), the final product in the action of light on visual purple. It is reconverted into visual purple by the regenerating action of the choroidal epithelium.

{Visual yellow} (Physiol.), a product intermediate between visual purple and visual white, formed in the photochemical action of light on visual purple. [1913 Webster]


The Collaborative International Dictionary of English. 2000.

Look at other dictionaries:

  • Visual angle — Angle An gle ([a^][ng] g l), n. [F. angle, L. angulus angle, corner; akin to uncus hook, Gr. agky los bent, crooked, angular, a gkos a bend or hollow, AS. angel hook, fish hook, G. angel, and F. anchor.] 1. The inclosed space near the point where …   The Collaborative International Dictionary of English

  • visual angle — n the angle formed by two rays of light or two straight lines drawn from the extreme points of a viewed object to the nodal point of the eye * * * the angle formed between two lines extending from the nodal point of the eye to the extremities of… …   Medical dictionary

  • Visual angle — The visual angle is the angle a viewed object subtends at the eye, usually stated in degrees of arc.It also is called the object s angular size. The sketch helps to define it 1,2It shows an observer s eye looking at a frontal extent (the vertical …   Wikipedia

  • visual angle — regos kampas statusas T sritis fizika atitikmenys: angl. visual angle vok. Gesichtswinkel, m; Sehwinkel, m rus. угол зрения, m pranc. angle visuel, m …   Fizikos terminų žodynas

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  • visual angle — noun : the angle formed by two rays of light or two straight lines drawn from the extreme points of a viewed object to the visual point of the eye …   Useful english dictionary

  • visual angle — noun Optics the angle formed at the eye by rays from the extremities of an object viewed …   English new terms dictionary

  • Visual Angle Illusion — The visual angle, V degrees, subtended by a viewed object sometimes looks larger or smaller than its actual value, creating a visual angle illusion (V illusion).These V illusions have been explicitly described by many vision researchers,… …   Wikipedia

  • Visual — Vis u*al, a. [L. visualis, from visus a seeing, sight: cf. F. visuel. See {Vision}.] 1. Of or pertaining to sight; used in sight; serving as the instrument of seeing; as, the visual nerve. [1913 Webster] The air, Nowhere so clear, sharpened his… …   The Collaborative International Dictionary of English

  • Visual cone — Visual Vis u*al, a. [L. visualis, from visus a seeing, sight: cf. F. visuel. See {Vision}.] 1. Of or pertaining to sight; used in sight; serving as the instrument of seeing; as, the visual nerve. [1913 Webster] The air, Nowhere so clear,… …   The Collaborative International Dictionary of English

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