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Focal Length

  • Reference work entry
  • First Online:
Computer Vision
  • 220 Accesses

Synonyms

Principal distance

Related Concepts

Center of Projection; Camera Calibration; Image Plane; Optical Axis; Pinhole Camera Model

Definition

The focal length has different, related, meanings. In optics, the focal length of a lens or optical system is the distance from the center to the point on the optical axis where a bundle of incoming rays parallel to the optical axis get focused to. In geometric image formation models such as the pinhole model, the focal length usually represents the distance between the center of projection and the image plane.

Background

The concept of focal length stems from the area of optics. The focal length of a lens is generally defined as the distance from the center of the lens to the point where a set of incoming parallel light rays that are parallel to the optical axis get focused. It is thus related to the magnification operated by an optical system.

In computer vision, the image formation process carried out by the optics and electronics of a...

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References

  1. Wikipedia (2011) Focal length. http://en.wikipedia.org/wiki/Focal_length. Accessed 3 August 2011

  2. Hecht E (2001) Optics. 4th edn. Addison, Wesley

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  3. Geissler P (2000) Imaging optics. In: Jähne B, Haußecker H (eds) Computer vision and applications. Academic, San Diego, pp 53–84

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  4. HyperPhysics (2011) Light and vision. http://hyperphysics.phy-astr.gsu.edu/hbase/ligcon.html#c1. Accessed 4 August 2011

  5. Wikipedia (2011) Lens (optics). http://en.wikipedia.org/wiki/Lens_(optics). Accessed 4 August 2011

  6. Wikipedia (2011) Thin lens. http://en.wikipedia.org/wiki/Thin_lens. Accessed 4 August 2011

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© 2014 Springer Science+Business Media New York

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Sturm, P. (2014). Focal Length. In: Ikeuchi, K. (eds) Computer Vision. Springer, Boston, MA. https://doi.org/10.1007/978-0-387-31439-6_464

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