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An engineering drawing is a type of technical drawing that is used to convey information about an object. ... Perspective projection
A 3D projection (or graphical projection) is a design technique used to display a three-dimensional (3D) object on a two-dimensional (2D) surface. These projections rely on visual perspective and aspect analysis to project a complex object for viewing capability on a simpler plane.
Linear or point-projection perspective (from Latin perspicere 'to see through') is one of two types of graphical projection perspective in the graphic arts; the other is parallel projection. [citation needed] [dubious – discuss] Linear perspective is an approximate representation, generally on a flat surface, of an image as it is seen by the eye.
Oblique projection is a simple type of technical drawing of graphical projection used for producing two-dimensional (2D) images of three-dimensional (3D) objects. The objects are not in perspective and so do not correspond to any view of an object that can be obtained in practice, but the technique yields somewhat convincing and useful results.
On engineering drawings, the projection is denoted by an international symbol representing a truncated cone in either first-angle or third-angle projection, as shown by the diagram on the right. The 3D interpretation is a solid truncated cone, with the small end pointing toward the viewer.
Technical illustration uses several basic mechanical drawing configurations called axonometric projection. These are: Parallel projections (oblique, planometric, isometric, dimetric, and trimetric), and; many types of perspective projections (with one, two, or three vanishing points).
In 5-point perspective the vanishing points are mapped into a circle with 4 vanishing points at the cardinal headings N, W, S, E and one at the circle's origin. A reverse perspective is a drawing with vanishing points that are placed outside the painting with the illusion that they are "in front of" the painting.
Projection planes are used often in descriptive geometry and graphical representation. A picture plane in perspective drawing is a type of projection plane. With perspective drawing, the lines of sight, or projection lines, between an object and a picture plane return to a vanishing point and are not parallel.