<P> A parallel projection is a particular case of projection in mathematics and graphical projection in technical drawing . Parallel projections can be seen as the limit of a central or perspective projection, in which the rays pass through a fixed point called the center or viewpoint, as this point is moved towards infinity . Put differently, a parallel projection corresponds to a perspective projection with an infinite focal length (the distance between the lens and the focal point in photography) or "zoom". In parallel projections, lines that are parallel in three - dimensional space remain parallel in the two - dimensional projected image . </P> <P> A perspective projection of an object is often considered more realistic than a parallel projection, since it more closely resembles human vision and photography . However, parallel projections are popular in technical applications, since the parallelism of an object's lines and faces is preserved, and direct measurements can be taken from the image . Among parallel projections, orthographic projections are the most realistic, and are commonly used by engineers . On the other hand, certain types of oblique projections (for example cavalier projection, military projection) are very simple to implement, and are used to create quick and informal pictorials of objects . </P> <P> The term parallel projection is used in the literature to describe both the procedure itself (a mathematical mapping function) as well as the resulting image produced by the procedure . </P> <P> Every parallel projection has the following properties . </P>

Parallel projection vs perspective projection in computer graphics