Editing Anisotropy (section)

===Remote sensing and radiative transfer modeling===
[[Radiance]] fields (see [[Bidirectional reflectance distribution function]] (BRDF)) from a reflective surface are often not isotropic in nature. This makes calculations of the total energy being reflected from any scene a difficult quantity to calculate. In [[remote sensing]] applications, anisotropy functions can be derived for specific scenes, immensely simplifying the calculation of the net reflectance or (thereby) the net [[irradiance]] of a scene.
For example, let the [[bidirectional reflectance distribution function|BRDF]] be <math>\gamma(\Omega_i, \Omega_v)</math> where 'i' denotes incident direction and 'v' denotes viewing direction (as if from a satellite or other instrument). And let P be the Planar Albedo, which represents the total reflectance from the scene.
<math display="block">P(\Omega_i) = \int_{\Omega_v} \gamma(\Omega_i, \Omega_v)\hat{n} \cdot d\hat\Omega_v</math>
<math display="block">A(\Omega_i, \Omega_v) = \frac{\gamma(\Omega_i, \Omega_v)}{P(\Omega_i)}</math>

It is of interest because, with knowledge of the anisotropy function as defined, a measurement of the [[bidirectional reflectance distribution function|BRDF]] from a single viewing direction (say, <math>\Omega_v</math>) yields a measure of the total scene reflectance (planar [[albedo]]) for that specific incident geometry (say, <math>\Omega_i</math>).