ORTHOGRAPHIC PROJECTION • Orthographic projection is the organization of multiple views of an object. In order to fully and accurately represent the object, more than one view is typically required. Principal Views of an Object • All orthographic projections are composed of six sides or planes of projection. All six views are not necessary to describe the object. Perpendicular Projection to Each Face • The lines of the object are projected perpendicular to the face to create each view. Each View Provides Two Measurements • a. Top and Bottom views show DEPTH and WIDTH. • b. Left and Right views show HEIGHT and DEPTH • c. Front and Rear views show HEIGHT and WIDTH. Measurement Transfer Between Views • The mitre line (drawn at a 45° angle) is used to transfer depth measurements between the top and right side (or left side) views. Normal Plane • Normal Planes will appear as an edge in two views and a true sized plan in the remaining view when using three views such as a top, front and right side. Inclined Plane • Inclined Planes will appear as an edge view in only one of the three views. The inclined plane will appear as a rectangular surface in the other two views. Oblique Planes • Oblique Planes will not appear as an edge view in any of the six views since they are not parallel or perpendicular to the projection planes. • They always appear as a “plane” and have the same number of corners in each of the six views. Curved Surfaces • A cylinder will appear as a circle in one view and a rectangular shape the other two views. Axis and Center Lines • The axis appears where the cylinder appears rectangular. • Center marks are used to identify the center of the cylinder where it appears circular.