The definition of the BSDF (Bidirectional scattering distribution function) is not well standardized. The term was probably introduced in 1991 by Paul Heckbert. Most often it is used to name the general mathematical function which describes the way in which the light is scattered by a surface. However in practice this phenomenon is usually split into the reflected and transmitted components, which are then treated separately as BRDF and BTDF (Bidirectional transmittance distribution function).
more from Wikipedia
Empirical research
Empirical research is a way of gaining knowledge by means of direct and indirect observation or experience. Empirical evidence (the record of one's direct observations or experiences) can be analyzed quantitatively or qualitatively. Through quantifying the evidence or making sense of it in qualitative form, a researcher can answer empirical questions, which should be clearly defined and answerable with the evidence collected (usually called data).
more from Wikipedia
Radiative transfer equation and diffusion theory for photon transport in biological tissue
Photon transport in biological tissue can be equivalently modeled numerically with Monte Carlo simulations or analytically by the radiative transfer equation (RTE). However, the RTE is difficult to solve without introducing approximations. A common approximation summarized here is the diffusion approximation. Overall, solutions to the diffusion equation for photon transport are more computationally efficient, but less accurate than Monte Carlo simulations.
more from Wikipedia
Albedo
Albedo, or reflection coefficient, derived from Latin albedo "whiteness" (or reflected sunlight), in turn from albus "white", is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it. Being a dimensionless fraction, it may also be expressed as a percentage, and is measured on a scale from zero for no reflecting power of a perfectly black surface, to 1 for perfect reflection of a white surface.
more from Wikipedia
Mean free path
In physics, the mean free path is the average distance travelled by a moving particle between successive impacts (collisions) which modify its direction or energy or other particle properties.
more from Wikipedia
Refractive index
In optics the refractive index (or index of refraction) n of a substance is a number that describes how light, or any other radiation, propagates through that medium. Its most elementary occurrence (and historically the first one) is in Snell's law of refraction, n1sin¿1= n2sin¿2, where ¿1 and ¿2 are the angles of incidence of a ray crossing the interface between two media with refractive indices n1 and n2.
more from Wikipedia
Angle of incidence
Angle of incidence is a measure of deviation of something from "straight on", for example: in the approach of a ray to a surface, or the angle at which the wing or horizontal tail of an airplane is installed on the fuselage, measured relative to the axis of the fuselage.
more from Wikipedia