page_title: Orthographic projection
section_title: Sub-types
hierarchical_section_title: Orthographic projection / Sub-types
context_page_description: Orthographic projection is a means of representing three-dimensional objects in two dimensions. It is a form of parallel projection, in which all the projection lines are orthogonal to the projection plane, resulting in every plane of the scene appearing in affine transformation on the viewing surface. The obverse of an orthographic projection is an oblique projection, which is a parallel projection in which the projection lines are not orthogonal to the projection plane.
  The term orthographic is sometimes reserved specifically for depictions of objects where the principal axes or planes of the object are also parallel with the projection plane, but these are better known as multiview projections. Furthermore, when the principal planes or axes of an object in an orthographic projection are not parallel with the projection plane, but are rather tilted to reveal multiple sides of the object, the projection is called an axonometric projection. Sub-types of multiview projection include plans, elevations and sections. Sub-types of axonometric projection include isometric, dimetric and trimetric projections.
context_section_description: With multiview projections, up to six pictures of an object are produced, with each projection plane parallel to one of the coordinate axes of the object. The views are positioned relative to each other according to either of two schemes: first-angle or third-angle projection. In each, the appearances of views may be thought of as being projected onto planes that form a six-sided box around the object. Although six different sides can be drawn, usually three views of a drawing give enough information to make a three-dimensional object. These views are known as front view, top view and end view. Other names for these views include plan, elevation and section.
  The term axonometric projection (not to be confused with the related principle of axonometry, as described in Pohlke's theorem) is used to describe the type of orthographic projection where the plane or axis of the object depicted is not parallel to the projection plane, and where multiple sides of an object are visible in the same image. It is further subdivided into three groups: isometric, dimetric and trimetric projection, depending on the exact angle at which the view deviates from the orthogonal. A typical characteristic of axonometric projection (and other pictorials) is that one axis of space is usually displayed as vertical.
caption: Symbols used to define whether a multiview projection is either third-angle (right) or first-angle (left).