projection


projection
projectional /preuh jek"sheuh nl/, adj.
/preuh jek"sheuhn/, n.
1. a projecting or protruding part.
2. the state or fact of jutting out or protruding.
3. a causing to jut or protrude.
4. the act, process, or result of projecting.
5. Cartog. a systematic construction of lines drawn on a plane surface representative of and corresponding to the meridians and parallels of the curved surface of the earth or celestial sphere.
6. Photog.
a. the act of reproducing on a surface, by optical means, a remote image on a film, slide, etc.
b. an image so reproduced.
7. the act of visualizing and regarding an idea or the like as an objective reality.
8. something that is so visualized and regarded.
9. calculation of some future thing: They fell short of their projection for the rate of growth.
10. the act of communicating distinctly and forcefully to an audience.
11. Psychol.
a. the tendency to ascribe to another person feelings, thoughts, or attitudes present in oneself, or to regard external reality as embodying such feelings, thoughts, etc., in some way.
b. Psychoanal. such an ascription relieving the ego of a sense of guilt or other intolerable feeling.
12. the act of planning or scheming.
13. Alchemy. the casting of the powder of philosophers' stone upon metal in fusion, to transmute it into gold or silver.
[1470-80; < L projection- (s. of projectio) a throwing forward. See PROJECT, -ION]
Syn. 1. jut, overhang, protrusion. 9. prediction.

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      in cartography, systematic representation on a flat surface of features of a curved surface, as that of the Earth. Such a representation presents an obvious problem but one that did not disturb ancient or medieval cartographers. Only when the voyages of exploration stimulated production of maps showing entire oceans, hemispheres, and the whole Earth did the question of projection come to the fore. Mercator produced the simplest and, for its purposes, the best solution by in effect converting the spherical Earth into a cylinder with the open ends at the poles; this cylinder was then opened to form a plane surface. East–west and north–south directions could be represented with fidelity, and the distortions in size became gross only near the polar regions (rendering Greenland, for example, disproportionately large). The Mercator projection is still widely used, especially when north–south dimensions are of chief importance. Many other projections are used, for example, the conic projection, drawn from a point directly above the North or South Pole. All projections involve some degree of distortion, and those showing the entire Earth involve a large degree.

 in geometry, a correspondence between the points of a figure and a surface (or line). In plane projections, a series of points on one plane may be projected onto a second plane by choosing any focal point, or origin, and constructing lines from that origin that pass through the points on the first plane and impinge upon the second (see illustration—>). This type of mapping is called a central projection. The figures made to correspond by the projection are said to be in perspective, and the image is called a projection of the original figure. If the rays are parallel instead, the projection is likewise called “parallel”; if, in addition, the rays are perpendicular to the plane upon which the original figure is projected, the projection is called “orthogonal.” If the two planes are parallel, then the configurations of points will be identical; otherwise this will not be true.

      A second common type of projection is called stereographic projection. It refers to the projection of points from a sphere to a plane. This may be accomplished most simply by choosing a plane through the centre of the sphere and projecting the points on its surface along normals, or perpendicular lines, to that plane. In general, however, projection is possible regardless of the attitude of the plane. Mathematically, it is said that the points on the sphere are mapped onto the plane; if a one-to-one correspondence of points exists, then the map is called conformal.

       projective geometry (q.v.) is the discipline concerned with projections and the properties of projective configurations.

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Universalium. 2010.

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  • projection — [ prɔʒɛksjɔ̃ ] n. f. • 1314; lat. projectio, de projectus, p. p. de projicere 1 ♦ Action de jeter, de lancer en avant (⇒ 1. jet; projeter, I ). Projection de liquide, de vapeur. Lancement, jet (de projectiles). Projection de pierres, d obus.… …   Encyclopédie Universelle

  • Projection — Pro*jec tion, n. [L. projectio: cf. F. projection.] [1913 Webster] 1. The act of throwing or shooting forward. [1913 Webster] 2. A jutting out; also, a part jutting out, as of a building; an extension beyond something else. [1913 Webster] 3. The… …   The Collaborative International Dictionary of English

  • projection — Pro*jec tion, n. [L. projectio: cf. F. projection.] [1913 Webster] 1. The act of throwing or shooting forward. [1913 Webster] 2. A jutting out; also, a part jutting out, as of a building; an extension beyond something else. [1913 Webster] 3. The… …   The Collaborative International Dictionary of English

  • projection — projection, protrusion, protuberance, bulge all denote something which extends beyond a level or a normal outer surface. Projection is applicable to anything that juts out, especially at a sharp angle {buttresses are projections which serve to… …   New Dictionary of Synonyms

  • projection — [prō jek′shən, prəjek′shən] n. [MFr < L projectio] 1. a projecting or being projected 2. something that projects, or juts out 3. something that is projected; specif., in map making, the representation on a plane of the earth s surface (or the… …   English World dictionary

  • projection — 1550s, originally cartographical, drawing of a map or chart according to scale, from M.Fr. projection, from L. projectionem (nom. projectio), from projicere (see PROJECT (Cf. project) (n.)) …   Etymology dictionary

  • projection — [n1] bulge, overhang bump, bunch, eaves, extension, hook, jut, knob, ledge, outthrust, point, prolongation, prominence, protrusion, protuberance, ridge, rim, shelf, sill, spine, spur, step, swelling; concepts 471,509,513 Ant. depression… …   New thesaurus

  • projection — Projection. s. f. v. Il n a guere d usage qu en cette phrase, Poudre de projection, qui se dit d une poudre par laquelle les Chymistes pretendent faire le changement des métaux en or …   Dictionnaire de l'Académie française

  • Projection — (v. lat.), 1) der Wurf, das Werfen; 2) die Abbildung eines Gegenstandes auf einer ebenen od. krummen Fläche durch gerade Linien, welche sich entweder parallel sind, od. nach einem gegebenen Punkte zusammenlaufen. Wenn auf zwei einander… …   Pierer's Universal-Lexikon

  • Projection — Projection, die geometrischen Beziehungen beliebiger Punkte, Linien und Flächen im Raume zu 1, 2 oder 3 sich gegenseitig schneidenden gegebenen Ebenen. Erstere sind die projicirenden Punkte etc., letzteres die P. s od. Coordinatenebenen.… …   Herders Conversations-Lexikon

  • projection TV — n. a system made up of lenses, mirrors, and a cathode ray tube, for projecting video images onto a large screen * * * …   Universalium


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