RAMI website

Homogeneous discrete cases with anisotropic background


This set of experiments is suggested to simulate the radiative transfer regime in the RAMI-V spectral bands homogeneous canopies composed of a large number of non overlapping disc-shaped objects representing the foliage elements, distributed over a horizontal background surface with different non-lambertian reflectance properties. Six flavors of the scene originates from the combination of two by three different surface parametrizations as listed in Table 1.

HOMnn_DIS_l1r Leaf distribution Surface reflectance
HOM23_DIS_P1A planophile A (soil, RPV4_)
HOM24_DIS_P1B planophile B (snow, RPV8_)
HOM25_DIS_P1C planophile C (understorey vegetation, RPVS_)
HOM33_DIS_E1A erectophile A
HOM34_DIS_E1B erectophile B
HOM35_DIS_E1C erectophile C
Table 1: scenes flavors as a combination of two vegetation type and three surface reflectance properties.

To address the needs of different RT models, both a statistical scene description, as well as a file with the exact coordinates of every single scatterer in the canopy are provided. The BRF of the anisotropically scattering background (which is intended to represent bare soil, snow and understorey vegetation conditions) are expressed with the parametric RPV model.

The foliage objects are randomly distributed finite size disc-shaped scatterers characterized by leaf angle distributions typical of a planophile and an erectophile canopies. The header of the files which describe the leaf center positions (Xc, Yx, Zc) and their angular orientation through the cosines of the angles with respect the x, y, z axes. The header for both files is: R Xc Yc Zc Dx Dy Dz.

The details are given in Table 2.

Properties Planophile Erectophile
Scene dimension 25 x 25 x 1 m
Leaf center (Xmin, Ymin, Zmin) -12.450, -12.450, 0.100 m
Leaf center (Xmax, Ymax, Zmax) 12.499. 12.499, 1.000 m
Scatterer Radious 0.05 m
Leaf area index 1 $m^2/m^2$
Height of canopy 1 m
Number of leaves 79577
Scatterer normal distribution Planophile Erectophile
Leaf position and orientation link link
Table 2: Planophile and erectophile homogeneous scene physical properties.

Planophile scene statistics.
Figure 1: Planophile scene statistics.
Erectophile scene statistics.
Figure 2: Erectophile scene statistics.

Example of rendering for HOM23.
Figure 3: Example of rendering for HOM23.

Each leaf is characterized by a Bi-Lambertian optical properties through the STDL_REFL and STDL_TRAN spectral values given in here for each RAMI-V spectral band.

The BRF of the anisotropic scattering background (which is intended to represent bare soil, snow, and understorey vegetation conditions) is expressed in terms of $\rho_0$,k and $\Theta$ parameters of the RPV model. The parameters labeled with RPV4_ should be used for HET23, HET33 (soil background), RPV8_ for HET24, HET34 (snow background) and RPVS_ for HET25, HET35 (understorey vegetation) scenes, can be found here.



The illumination conditions are very likely dependent on the kind of measurement in RAMI-V more than in previous RAMI phases. For brf*, dhr, fabs*, ftran* measurements, except brf_sat, the illumination were listed in the description of measure brfpp, and duplicated in other measure description pages. For these geometries the tag will be _zZZaAAA_ with ZZ and AAA defining $\theta_i$ and $\phi_i$, respectively. In addition, diffuse isotropic illumination is foreseen for bhr, fabs*, ftran* measures (geometry tag will then be _DIFFUSE_).