The method of developing multiview drawings is called Orthographic Projection Drawings. It permits three dimensional objects to be shown on a flat surface having only two dimensions. It reveals the width, depth and height of the objects. It assumes that a picture plane is parallel to each other being drawn and the image is projected to the picture plane with perpendicular lines. Orthographic drawings are useful especially when a design has been developed to a stage whereby it is almost ready to be implemented. There are two ways of drawing in orthographic - First Angle and Third Angle. They differ only in the position of the plan, front and side views. (Figure – 1) Additional planes can be added until a full description of the object is obtained.
Orthographic projection is a technique that is used to create multi view drawings. Orthographic projection is any projection of the features of an object onto an imaginary plane of projection. The projection of the features of the object is made by lines of sight that are perpendicular to the plane of projection. A projection plane, also referred to as a plane of projection or picture plane, is an imaginary surface that exists between the viewer and the object. The projection plane is the surface onto which a two-dimensional view of a three-dimensional object is projected and created. Projection lines are used to project each corner outward until they reach the projection plane. A projection line is an imaginary line that is used to locate or project the corners, edges, and features of a three-dimensional object onto an imaginary two-dimensional surface.
The visible edges of the object are then identified on the projection plane by connecting the projected corners with object lines.
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