Light Vector

The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Light Vector


The light vector determines the magnitude and direction of transfer of that part of the energy of electromagnetic radiation that can be visually perceived. In other words, it determines the magnitude and direction of the luminous flux. The absolute value of the light vector is the ratio of the luminous energy transferred across an area ΔS in a unit of time to ΔS under the condition that the transfer (the direction of the light vector) is perpendicular to ΔS. The concept of the light vector is used mainly in theoretical photometry for the quantitative description of light fields and is the photometric analogue of the Poynting vector. The divergence of the light vector determines the volume density of absorption or emission of light at a given point of a light field.

Sometimes, especially in older scientific literature, the electric field strength vector E of an electromagnetic wave is called the light vector.


The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Given a light vector, the reflectance R and the transmission on the surface can be calculated using Ward's BRDF model [15] or other reflection models.
where ([[theta].sub.i], [[phi].sub.i]) is the incident light vector and ([[theta].sub.r], [[phi].sub.r]) is the reflected light vector.
The medium modifications of Kaons, D mesons, and light vector mesons had been studied using different theoretical approaches, for example, chiral model [5-13], QCD sum rules [14-19], and coupled channel approach [20-22].
For a linear photodiode array with length L, a light vector falls at an angle 0 from the normal along the element axis and at an angle 0 from the normal along the perpendicular to the element axis.
I represents the light intensity, while [theta] is an angle between the normal vector and the light vector. [[Alpha].sub.x], [[alpha].sub.y] are the standard deviations of the surface slope in the x, y directions, and [delta] is the angle between the normal vector and the half vector H.
The next step is to do a real-time dot product of the normal map and our light vector. This can be done by multitexturing the normal map texture with a normalization cube map, that is rotated according to the direction of our light source [2].
It seems that global bending within the fiber increased the incidence angle d0 of (1), leading to more number of reflected light vectors outside the fiber core.
Our previous work [1] used a small-time-step-based ray-tracing strategy, in which light vectors advanced by the length of its wavelength at each time frame.