HOM26,27,28/HOM36,37,38
This set of experiments is suggested to simulate the radiative transfer regime in the RAMI-V spectral bands for spatially homogeneous leaf canopies composed of two different horizontal layers (reminiscent of the overstorey and understorey of plant canopies). Each layer contains a large number of non overlapping disc-shaped objects representing the foliage elements.
| HOMnn_DIS_lld | Overstorey (LAI=1.0 $m^2/m^2$) | Understorey (variable LAI) |
|---|---|---|
| HOM26_DIS_EPD | Erectophile Sparse | Planophile Dense |
| HOM27_DIS_EPM | Erectophile Sparse | Planophile Medium |
| HOM28_DIS_EPS | Erectophile Sparse | Planophile Sparse |
| HOM36_DIS_PED | Planophile Sparse | Erectophile Dense |
| HOM37_DIS_PEM | Planophile Sparse | Erectophile Medium |
| HOM38_DIS_PES | Planophile Sparse | Erectophile Sparse |
The foliage objects are randomly distributed finite size disc-shaped scatterers characterized by the specified radiative properties (reflectance, transmittance) for each layer, and the orientation of the normals to the scatterers which follow erectophile and planophile distribution functions. The particular values selected for the various input variables represent typical plant canopy conditions.
HOM26 to HOM28 refer to canopies with a 1 m thick top layer, characterized by an erectophile leaf angle distribution (LAD), formed by disc-shaped elements with a scatterer radius of 0.05 m, and a fixed LAI of 1 $m^2/m^2$, combined with a bottom layer featuring a planophile LAD, identical scatterer radius (0.05 m) and height (1 m) as the top layer, but for three different LAI values (5.0, 2.0 and 1.0 $m^2/m^2$). The overall canopy height is 2 m.
For 3D RT models capable of using the deterministic position and orientation of all scatterers in the scenes three ASCII files are provided that contain the layer ID (TLL=top layer leaf and BLL=bottom layer leaf), the leaf/disc radius (R), the leaf/disc centre coordinates (Xc,Yc,Zc), and the direction cosines (Dx,Dy,Dz) of every single leaf/disc in a 25×25 $m^2$ canopy section. The size of these ASCII files is several Mbytes and the format of its content is L_id R Xc Yc Zc Dx Dy Dz. The deterministic foliage location and orientation information can be found via the next three links: HOM26 (20.7 Mbytes), HOM27 (10.4 Mbytes), and HOM28 (6.9 Mbytes).
HOM36 to HOM38 refer to canopies with a 1 m thick top layer, with a planophile LAD, formed by disc-shaped scatterer (R = 0.05m), and a LAI 1 $m^2/m^2$, combined with a bottom layer featuring an erectophile LAD, identical scatterer radius (0.05m) and height (1m) as the top layer, and three different LAI values (5.0, 2.0 and 1.0 $m^2/m^2$). The overall canopy height is 2m. The deterministic foliage location and orientation information can be found via the next three links: HOM36 (20.7 Mbytes), HOM37 (10.4 Mbytes), and HOM38 (6.9 Mbytes).
The leaf reflectance and transmittance of the TOP layer are defined by the tag LEAF1 tag in file. The spectral properties of the BOTTOM layer are defined by the LEAF2 tag.
The scattering laws of (both sides of the) foliage elements and the background surface are Lambertian.
The surface reflectance is Lambertian and defined by the SOIL2_REFL of the spectral file.
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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_).
