This set of experiments was suggested to evaluate the models under extreme conditions, in particular to verify their ability to conserve energy. The proposed scenes constitute a special case of an homogeneous environment in which the values selected for the input variables were not meant to represent any particular realistic conditions, but, rather, to permit a detailed evaluation of the performance of the participating models. Two types of homogeneous environments are being considered:
Homogeneous environments are typically represented with 1-dimensional models, where the only spatial coordinate represented explicitly is along the vertical. However, for the case of finite-sized scatterers, the geophysical medium is intrinsically 3-dimensional, since the individual scatterers are oriented finite size objects, even though it may be simulated statistically without an explicit representation of horizontal variations.
In absence of any absolute reference truth RT model performance can be expressed in terms of the deviation between some model m and another model c from among the ensemble of models that performed a given set of spectral (lambda), structural (zeta), illumination (Omega_i) and viewing (Omega_v) conditions. Averaging over an appropriate set of such conditions will allow to compute a (delta_m<->c) model-to-model dispersion statistics [%]:
is the total number of all spectral (lambda), structural (zeta), illumination(Omega_i) and viewing (Omega_v) conditions used in the averageing.