Orthographic Projection

Orthographic Projection

Orthographic Projection• The word orthographic means to draw at right

angles and it is derived from the Greek words:• ORTHOS - straight, rectangular, upright• GRAPHOS - written, drawn• There are two predominant orthographic

projections used today. • They define four separate spaces, or quadrants.

Each of these quadrants could contain the object to be represented. Traditionally however, only two are commonly used, the first and the third angle projection.

Orthographic Projection• Projections created with the object placed in the first

quadrant are said to be in First Angle projection• Projections created with the object placed in the third

quadrant are said to be in Third Angle projection.

ORTHOGRAPHIC VIEWS • Orthographic Views are two-dimensional views of

objects where the viewpoint of the object is at right angles to (or looking directly at) surfaces. They are used in technical and engineering drawings for accuracy. If one's viewpoint is not at right angles, it is considered a "Foreshortened" view.

ORTHOGRAPHIC VIEWS • Because the views are only two dimensional, more

than one view is needed to completely describe the object. Usually two or three views is enough (Front, Top and Side), but often more are required.

Angle of Orthogonal ProjectionFirst Angle Projection• Each view is placed opposite to the side from which

they are viewed. Example, Left view is presented in the Right side of the

Front view.Third Angle Projection• Each view is placed adjacent to the side from which

they are viewed. Example, Left view is presented in the Left side of the

Front view.AS1100 recommends the Third Angle Projection.

Orthogonal Projection

Illustrations of the visible lines and parallel planes

Illustrations of the objects having hidden features

Illustrations of the objects having the sloping surfaces

Illustrations of the objects having circular features