The Description of Forms Working Document Linguistic review 29-09-07

The Description of Forms A drawing of an object is a projection that relates: an object; a base; an observer; projecting lines or lines of vision.

To project is: [MATHEMATICS] the operation by which we make all points on a given surface correspond to a point on another surface; The action of projecting an image on a screen.

Types of projections PROJECTIONS CONICAL PROJECTIONS PARALLEL OBLIQUE PROJECTIONS ORTHOGRAPHIC PROJECTIONS AXONOMETRIC MULTI-VIEW

Conical projections In this type of drawing, the observer is relatively close to the projection plane. The lines of vision thus form a cone directed towards the observer’s eye.

Parallel projections In this type of drawing, the observer is infinitely far away. The lines of vision then become parallel. In addition, if the object is perpendicular to the projection plane, the projection is said to be orthographic.

Oblique projections The observer is still an infinite distance from the object, the projecting lines remain parallel to one another, but the object is placed in such a way that the lines of vision are oblique in relation to the projection plane.

PROJECTIONS PARALLEL ORTHOGRAPHIC CONICAL OBLIQUE AXONOMETRIC MULTI-VIEW

Bibliography GIESECKE, Frederick E., MITCHELL, Alva, SPENCER, Henry Cecil, HILL, Ivan Leroy, GYGDON, John Thomas et NGUYEN, Dinh N. « Dessin technique », Montréal, Éditions du Renouveau Pédagogique inc., 1982, 769 p. JENSEN, C.H. « Dessin industriel », Montréal, McGraw-Hill, 1972, 752 p. STIRLING, Norman. « Éléments de dessin industriel », Montréal, HRW, 1979, 372 p.