Phase: RAMI2
Within this section of the RAMI initiative homogeneous environments have to be simulated where scatterers possess the typical optical properties of vegetation in the red and near-infrared spectral domain. 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.
Results for discrete homogeneous scenes are exhibited in the following Figure, which shows the various contributions of the models to a series of histograms of local angular model deviation values estimated for viewing conditions in the principal plane (left panels), cross plane (middle panels) and the principal and cross planes together (right panels). The top, center and bottom panels display the results obtained at the red, the near-infrared and, at the red and near-infrared wavelengths together, respectively. As such, this figure demonstrates the large spread of results delivered by a set of 8 BRF models participating.
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 figure displays the angular deviations of the various models (with respect to each other) as a function of viewing angle, averaged over both erectophile and planophile leaf normal distributions in the case of the discrete homogeneous environments, along the principal plane, at two solar zenith angles (20 and 50 degree), and for both the red and near-infrared wavelengths:
The following figure is similar to the previous but shows the angular deviations of the various models (with respect to each other) as a function of viewing angle, averaged over both erectophile and planophile leaf normal distributions in the case of the discrete homogeneous environments, along the orthogonal plane, at two solar zenith angles (20 and 50 degree), and for both the red and near-infrared wavelengths:
The various testcases that are defined within this phase of the RAMI initiative can be visualized on their respective description pages: