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The field of view (FoV) is the extent of the observable world that is
seen Seen may refer to: * Seen (album), ''Seen'' (album), by Tom Bailey * Seen (artist), graffiti artist * Seen (Winterthur), a district of the city of Winterthur, Switzerland * Arabic letter Shin (letter)#Arabic šīn, seen س See also

*Xian (disam ...
at any given moment. In the case of
optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and determine their characteristic properties. Common examples include periscopes, microscopes, ...
s or sensors it is a
solid angle In geometry, a solid angle (symbol: ) is a measure of the amount of the field of view from some particular point that a given object covers. That is, it is a measure of how large the object appears to an observer looking from that point. The poi ...

solid angle
through which a detector is sensitive to
electromagnetic radiation In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related entities of energy and force. ...

electromagnetic radiation
.


Humans and animals

In the context of human and primate vision, the term "field of view" is typically only used in the sense of a restriction to what is visible by external apparatus, like when wearing spectacles or
virtual reality Virtual reality (VR) is a simulated experience that can be similar to or completely different from the real world. Applications of virtual reality Virtual reality applications are applications that make use of virtual reality Virtual ...

virtual reality
goggles. Note that eye movements are allowed in the definition but do not change the field of view when understood this way. If the analogy of the eye's retina working as a sensor is drawn upon, the corresponding concept in human (and much of animal vision) is the
visual field The visual field is the "spatial array of visual sensations available to observation in introspection Introspection is the examination of one's own conscious thoughts and feelings. In psychology, the process of introspection relies on the observ ...
. It is defined as "the number of degrees of visual angle during stable fixation of the eyes".Strasburger, Hans; Pöppel, Ernst (2002). Visual Field. In G. Adelman & B.H. Smith (Eds): ''Encyclopedia of Neuroscience''; 3rd edition, on CD-ROM. Elsevier Science B.V., Amsterdam, New York. Note that eye movements are excluded in the visual field's definition. Different animals have different visual fields, depending, among others, on the placement of the eyes.
Humans Humans (''Homo sapiens'') are the most abundant and widespread species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A speci ...

Humans
have a slightly over 210-degree forward-facing horizontal arc of their visual field (i.e. without eye movements), (with eye movements included it is slightly larger, as you can try for yourself by wiggling a finger on the side), while some
birds Birds are a group of warm-blooded vertebrate Vertebrates () comprise all species of animal Animals (also called Metazoa) are multicellular eukaryotic organisms that form the Kingdom (biology), biological kingdom Animalia. With ...
have a complete or nearly complete 360-degree visual field. The vertical range of the visual field in humans is around 150 degrees. The range of visual abilities is not uniform across the visual field, and by implication the FoV, and varies between
species In biology, a species is the basic unit of biological classification, classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individu ...

species
. For example,
binocular vision Binocular may refer to: Science and technology * Binocular vision In , binocular vision is a type of in which an animal has two s capable of facing the same direction to perceive a single of its surroundings. Neurological researcher Manfred ...

binocular vision
, which is the basis for
stereopsis Stereopsis (from the Greek#REDIRECT Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is appro ...
and is important for
depth perception Depth perception is the ability to perceive the world in three s () and the distance of an object. Depth sensation is the corresponding term for non-human animals, since although it is known that they can sense the distance of an object (becaus ...
, covers 114 degrees (horizontally) of the visual field in humans; the remaining peripheral 40 degrees on each side have no binocular vision (because only one
eye Eyes are organs of the visual system. They provide living organisms with vision, the ability to receive and process visual detail, as well as enabling several photo response functions that are independent of vision. Eyes detect light L ...

eye
can see those parts of the visual field). Some birds have a scant 10 to 20 degrees of binocular vision. Similarly,
color vision Color vision, a feature of visual perception Visual perception is the ability to interpret the surrounding environment (biophysical), environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and ...

color vision
and the ability to perceive shape and motion vary across the visual field; in humans color vision and form perception are concentrated in the center of the visual field, while motion perception is only slightly reduced in the periphery and thus has a relative advantage there. The physiological basis for that is the much higher concentration of color-sensitive
cone cell Cone cells, or cones, are photoreceptor cells A photoreceptor cell is a specialized type of neuroepithelial cell found in the retina The retina (from la, rete) is the innermost, light-sensitive layer of tissue of the eye of most ve ...

cone cell
s and color-sensitive parvocellular
retinal ganglion cell A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the human eye, eye. It receives visual information from photoreceptor cell, photoreceptors via two intermediate neuron typ ...
s in the fovea – the central region of the retina, together with a larger representation in the visual cortex – in comparison to the higher concentration of color-insensitive
rod cell Rod cells are photoreceptor cell A photoreceptor cell is a specialized type of neuroepithelial cellNeuroepithelial cells, or neuroectodermal cells, form the wall of the closed neural tube in early embryonic development ''Embryonic'' is th ...
s and motion-sensitive magnocellular
retinal ganglion cell A retinal ganglion cell (RGC) is a type of neuron located near the inner surface (the ganglion cell layer) of the retina of the human eye, eye. It receives visual information from photoreceptor cell, photoreceptors via two intermediate neuron typ ...
s in the visual periphery, and smaller cortical representation. Since rod cells require considerably less light to be activated, the result of this distribution is further that peripheral vision is much more sensitive at night relative to foveal vision (sensitivity is highest at around 20 deg eccentricity).


Conversions

Many optical instruments, particularly
binoculars Binoculars or field glasses are two telescope A telescope is an optical instrument An optical instrument (or "optic" for short) is a device that processes light waves (or photons), either to enhance an image for viewing or to analyze and ...
or spotting scopes, are advertised with their field of view specified in one of two ways: angular field of view, and linear field of view. Angular field of view is typically specified in degrees, while linear field of view is a ratio of lengths. For example, binoculars with a 5.8 degree (angular) field of view might be advertised as having a (linear) field of view of 102 mm per meter. As long as the FOV is less than about 10 degrees or so, the following approximation formulas allow one to convert between linear and angular field of view. Let A be the angular field of view in degrees. Let M be the linear field of view in millimeters per meter. Then, using the
small-angle approximation The small-angle approximations can be used to approximate the values of the main trigonometric functions, provided that the angle in question is small and is measured in radians: : \begin \sin \theta &\approx \theta \\ \cos \theta &\approx 1 - \ ...
: :A \approx \cdot \approx 0.0573 \times M :M \approx \cdot A \approx 17.45 \times A


Machine vision

In
machine vision Machine vision (MV) is the technology and methods used to provide imaging-based automatic inspection and analysis for such applications as automatic inspection, process control, and robot guidance, usually in industry. Machine vision refers to ma ...

machine vision
the lens
focal length The focal length of an optical Optics is the branch of physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

focal length
and
image sensor An image sensor or imager is a sensor A sensor is a device that produces an output signal for the purpose of sensing of a physical phenomenon. In the broadest definition, a sensor is a device, module, machine, or subsystem that detects e ...
size sets up the fixed relationship between the field of view and the working distance. Field of view is the area of the inspection captured on the camera’s imager. The size of the field of view and the size of the camera’s imager directly affect the image resolution (one determining factor in accuracy). Working distance is the distance between the back of the lens and the target object.


Tomography

In
tomography File:Sagittal brain MRI.jpg, thumbnail, Median plane Sagittal plane, sagittal tomography of the head by magnetic resonance imaging. Tomography is image, imaging by sections or sectioning through the use of any kind of penetrating wave. The method i ...
, the field of view is the area of each tomogram. In for example
computed tomography A CT scan or computed tomography scan (formerly known as computed axial tomography or CAT scan) is a medical imaging Imaging is the representation or reproduction of an object's form; especially a visual representation (i.e., the formation of ...

computed tomography
, a volume of
voxel In 3D computer graphics 3D computer graphics, sometimes called CGI, 3DCG or three-dimensional computer graphics (in contrast to 2D computer graphics 2D computer graphics is the Computer-generated imagery, computer-based generation of digita ...

voxel
s can be created from such tomograms by merging multiple slices along the scan range.


Remote sensing

In
remote sensing Remote sensing is the acquisition of information about an object or phenomenon without making physical contact with the object, in contrast to in situ ''In situ'' (; often not italicized in English) is a Latin Latin (, or , ) is a class ...

remote sensing
, the
solid angle In geometry, a solid angle (symbol: ) is a measure of the amount of the field of view from some particular point that a given object covers. That is, it is a measure of how large the object appears to an observer looking from that point. The poi ...

solid angle
through which a detector element (a pixel sensor) is sensitive to electromagnetic radiation at any one time, is called ''instantaneous field of view'' or IFOV. A measure of the
spatial resolution In physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space and time, and the related entities of energy and force. "Phy ...
of a remote sensing imaging system, it is often expressed as dimensions of visible ground area, for some known sensor
altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference and a point or object. The exact definition and reference datum varies according to the context (e.g. ...

altitude
. Single pixel IFOV is closely related to concept of ''resolved pixel size'', ground resolved distance,
ground sample distanceIn remote sensing, ground sample distance (GSD) in a digital photo (such as an orthophoto) of the ground from air or space is the distance between pixel centers measured on the ground. For example, in an image with a one-meter GSD, adjacent pixels im ...
and
modulation transfer function The optical transfer function (OTF) of an optical system such as a camera, microscope, human eye, or image projector, projector specifies how different spatial frequencies are handled by the system. It is used by optical engineers to describe how ...
.


Astronomy

In
astronomy Astronomy (from el, ἀστρονομία, literally meaning the science that studies the laws of the stars) is a natural science that studies astronomical object, celestial objects and celestial event, phenomena. It uses mathematics, phys ...
, the field of view is usually expressed as an viewed by the instrument, in
square degree __NOTOC__ A square degree (deg2) is a non-SI Units of measurement, unit measure of solid angle. Other denotations include ''sq. deg.'' and (°)2. Just as degree (angle), degrees are used to measure parts of a circle, square degrees are used to meas ...
s, or for higher magnification instruments, in square
arc-minute A minute of arc, arcminute (arcmin), arc minute, or minute arc, denoted by the symbol , is a unit of Angular unit, angular measurement equal to of one Degree (angle), degree. Since one degree is of a turn (geometry), turn (or complete rotati ...
s. For reference the Wide Field Channel on the
Advanced Camera for Surveys in Maryland, prior to its installation on the Hubble Space Telescope Image:ACS FOC swap.jpg, Astronauts remove the Faint Object Camera, FOC to make room for the ACS, Year : 2002 The Advanced Camera for Surveys (ACS) is a third-generation axial in ...

Advanced Camera for Surveys
on the
Hubble Space Telescope The Hubble Space Telescope (often referred to as HST or Hubble) is a space telescope A space telescope or space observatory is a telescope in outer space used to observe astronomical objects. Suggested by Lyman Spitzer in 1946, the first ...

Hubble Space Telescope
has a field of view of 10 sq. arc-minutes, and the High Resolution Channel of the same instrument has a field of view of 0.15 sq. arc-minutes. Ground-based survey telescopes have much wider fields of view. The photographic plates used by the
UK Schmidt Telescope The UK Schmidt Telescope (UKST) is a 1.24 metre Schmidt telescope operated by the Australian Astronomical Observatory (formerly the Anglo-Australian Observatory); it is located adjacent to the 3.9 metre Anglo-Australian Telescope at Sid ...
had a field of view of 30 sq. degrees. The 1.8 m (71 in)
Pan-STARRS The Panoramic Survey Telescope and Rapid Response System (Pan-STARRS1; List of observatory codes, obs. code: IAU code#F51, F51 and Pan-STARRS2 obs. code: IAU code#F52, F52) located at Haleakala Observatory, Hawaii, US, consists of astronomical c ...
telescope, with the most advanced digital camera to date has a field of view of 7 sq. degrees. In the near infra-red WFCAM on has a field of view of 0.2 sq. degrees and the
VISTA Vista usually refers to a distant view. Vista may also refer to: Software *Windows Vista, the line of Microsoft Windows client operating systems released in 2006 and 2007 *VistA, (Veterans Health Information Systems and Technology Architecture) a ...
telescope has a field of view of 0.6 sq. degrees. Until recently digital cameras could only cover a small field of view compared to
photographic plate Photographic plates preceded photographic film Photographic film is a strip or sheet of transparent film baseA film base is a transparent substrate which acts as a support medium for the photosensitive emulsion An emulsion is a mixtu ...
s, although they beat photographic plates in
quantum efficiency In physics Physics (from grc, φυσική (ἐπιστήμη), physikḗ (epistḗmē), knowledge of nature, from ''phýsis'' 'nature'), , is the natural science that studies matter, its Motion (physics), motion and behavior through ...
, linearity and dynamic range, as well as being much easier to process.


Photography

In photography, the field of view is that part of the world that is visible through the camera at a particular position and orientation in space; objects outside the FOV when the picture is taken are not recorded in the photograph. It is most often expressed as the angular size of the view cone, as an
angle of view The angle of view is the decisive variable for the visual perception of the size or projection of the size of an object. Angle of view and perception of size The perceived size of an object depends on the size of the image projected onto the ...

angle of view
. For a normal lens, the diagonal (or horizontal or vertical) field of view can be calculated as: :\mathrm = 2 \times \arctan\left(\frac\right) where f is the
focal length The focal length of an optical Optics is the branch of physics Physics is the natural science that studies matter, its Elementary particle, fundamental constituents, its Motion (physics), motion and behavior through Spacetime, space ...

focal length
, here the sensor size and f are in the same unit of length, FOV is in radians.


Microscopy

In microscopy, the field of view in high power (usually a 400-fold
magnification Magnification is the process of enlarging the apparent size, not physical size, of something. This enlargement is quantified by a calculated number also called "magnification". When this number is less than one, it refers to a reduction in size, ...
when referenced in scientific papers) is called a high-power field, and is used as a reference point for various classification schemes. For an objective with magnification m, the FOV is related to the Field Number (FN) by :FOV = \frac, if other magnifying lenses are used in the system (in addition to the objective), the total m for the projection is used.


Video games

The field of view in
video game#REDIRECT Video game A video game is an electronic game that involves interaction with a user interface or input device such as a joystick, game controller, controller, computer keyboard, keyboard, or motion sensing device to generate visual f ...
s refers to the field of view of the camera looking at the game world, which is dependent on the scaling method used.


See also

*
Field of regardThe field of regard (abbreviated FOR) is the total area that can be captured by a movable sensor. It should not be confused with the field of view (FOV), which is the angular cone perceivable by the sensor at a particular time instant. The field of r ...
*
Panorama A panorama (formed from Greek Greek may refer to: Greece Anything of, from, or related to Greece Greece ( el, Ελλάδα, , ), officially the Hellenic Republic, is a country located in Southeast Europe. Its population is approximately ...

Panorama
*
Perimetry A visual field test is an eye examination that can detect dysfunction in central and peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, wh ...

Perimetry
*
Peripheral vision Peripheral vision, or ''indirect vision'', is vision as it occurs outside the point of fixation, i.e. away from the center of gaze or, when viewed at large angles, in (or out of) the "corner of one's eye". The vast majority of the area in the ...

Peripheral vision
*
Visual perception Visual perception is the ability to interpret the surrounding environment (biophysical), environment through photopic vision (daytime vision), color vision, scotopic vision (night vision), and mesopic vision (twilight vision), using light in ...
* Useful field of view * 35 mm equivalent focal length *
Angle of view The angle of view is the decisive variable for the visual perception of the size or projection of the size of an object. Angle of view and perception of size The perceived size of an object depends on the size of the image projected onto the ...

Angle of view
*
Crop factor In digital photography Digital photography uses cameras containing arrays of electronics, electronic photodetectors to produce images focused by a lens (optics), lens, as opposed to an exposure on photographic film. The captured images are di ...
*
Image sensor format In digital photography, the image sensor format is the shape and size of the image sensor. The image sensor format of a digital camera determines the angle of view of a particular lens when used with a particular sensor. Because the image se ...
*
Line of sight Line of sight (adjectival form line-of-sight) may refer to: Common meanings * Sightline, an unobstructed line-of-sight between a subject and object * Line of sight (gaming), visibility on a gaming field, ''i.e.'' who can see what Arts and enterta ...


References

{{Authority control Vision Ophthalmology Neurology Science of photography