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Glossary
Glossary and Index
G-2
Isotropic Source
A light source that emits light uniformly in all direcĆ
tions.
Luminance
The amount of light emitted or scattered by a
surface. Usually measured in candelas/meter
2
(nits)or footĆlamberts with a sensor spectrally
matched to the average human eye.
Luminous Flux
The total light from a source, measured in lumens
with a sensor spectrally matched to the average
human eye.
Luminous Intensity
The luminous flux through a unit of solid angle.
Usually measured in candelas (lumens/steradian)
with a sensor spectrally matched to the average
human eye.
Photometry
Measurement of light as seen by the human eye.
Photopic Correction
The correction of a sensor to match the CIE sensiĆ
tivity function of the average human eye.
Point Source
A light source of small angular size, such that light
appears to come from a point.
Radiance
The amount of radiant energy emitted or scattered
by a surface. Usually measured in watts/meĆ
ter
2
/steradian with a sensor having equal spectral
sensitivity to all wavelengths being measured.
Radiant Flux
The total radiation from a source, measured in
watts with a sensor having equal spectral sensitivity
to the wavelengths being measured.
Glossary
Glossary and Index
G-2
Isotropic Source
A light source that emits light uniformly in all direcĆ
tions.
Luminance
The amount of light emitted or scattered by a
surface. Usually measured in candelas/meter
2
(nits)or footĆlamberts with a sensor spectrally
matched to the average human eye.
Luminous Flux
The total light from a source, measured in lumens
with a sensor spectrally matched to the average
human eye.
Luminous Intensity
The luminous flux through a unit of solid angle.
Usually measured in candelas (lumens/steradian)
with a sensor spectrally matched to the average
human eye.
Photometry
Measurement of light as seen by the human eye.
Photopic Correction
The correction of a sensor to match the CIE sensiĆ
tivity function of the average human eye.
Point Source
A light source of small angular size, such that light
appears to come from a point.
Radiance
The amount of radiant energy emitted or scattered
by a surface. Usually measured in watts/meĆ
ter
2
/steradian with a sensor having equal spectral
sensitivity to all wavelengths being measured.
Radiant Flux
The total radiation from a source, measured in
watts with a sensor having equal spectral sensitivity
to the wavelengths being measured.