Projection
A projection is the transformation of Points and Lines in one Plane onto anotherPlane by connecting corresponding points on the two planes with Parallel lines. This can be visualized asshining a (point) light source (located at infinity) through a translucent sheet of paper and making an image of whatever isdrawn on it on a second sheet of paper. The branch of geometry dealing with the properties and invariants of geometricfigures under projection is called Projective Geometry.
The projection of a Vector 
onto a Vector 
is given by
and the length of this projection is
General projections are considered by Foley and VanDam (1983).See also Map Projection, Point-Plane Distance, Projective Geometry, Reflection
References
Casey, J. ``Theory of Projections.'' Ch. 11 in A Treatise on the Analytical Geometry of the Point, Line, Circle, and Conic Sections, Containing an Account of Its Most Recent Extensions, with Numerous Examples, 2nd ed., rev. enl. Dublin: Hodges, Figgis, & Co., pp. 349-367, 1893. Foley, J. D. and VanDam, A. Fundamentals of Interactive Computer Graphics, 2nd ed. Reading, MA: Addison-Wesley, 1990.
- Snake Polyiamond
- Snedecor's F-Distribution
- Snellius-Pothenot Problem
- Snowflake
- Snub Cube
- Snub Cuboctahedron
- Snub Disphenoid
- Snub Dodecadodecahedron
- Snub Dodecahedron
- Snub Icosidodecadodecahedron
- Snub Icosidodecahedron
- Snub Polyhedron
- Snub Square Antiprism
- Soap Bubble
- Soccer Ball
- Sociable Numbers
- Social Choice Theory
- Socrates' Paradox
- Soddy Circles
- Soddy Line
- Soddy Points
- Soddy's Hexlet
- Sofa Constant
- Soldner's Constant
- Solenoidal Field