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.
The following two Figures show the various contributions of the RT models to a series of histograms of local angular model deviation for discrete homogeneous environments with erectophile and planophile leaf normal distributions, respectively. Values were estimated for viewing conditions in the principal plane (left panels), cross plane (middle panels) and the principal and cross planes together (right panels) as well as for LAI values of 1 (top), 2 (center) and 5 (bottom).
The values obtained when estimating the local model deviation at the near-infrared wavelength reflects mainly the difference in the methods used to estimate the multiple scattering components in the plant-soil system. The following Figure thus shows the detailed contributions of the individual models to a series of histograms of local angular model deviation values for the multiple scattering component only (under the same conditions of averageing as before):
The following two figures displays the angular deviations of the various models (with respect to each other) as a function of viewing angle, for erectophile and planophile leaf normal distributions, respectively, along the principal plane, at three solar zenith angles: 0 (left), 30 (center) and 60 (right) degrees, and for LAI values of 1 (top), 2 (center) and 5 (bottom):
The following two figures are similar to the previous ones (first erectophile then planophile LNDs) but shows the angular deviations of the various models (with respect to each other) along the orthogonal plane, at three solar zenith angles: 0 (left), 30 (center) and 60 (right) degrees, and for LAI values of 1 (top), 2 (center) and 5 (bottom):
The various testcases that are defined within this phase of the RAMI initiative can be visualized on their respective description pages: