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17-May-2022   
Path: RAMI-IV : EXPERIMENTS : ABSTRACT CANOPIES : HOMOGENEOUS : ANISOTROPIC BACKGROUND
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Homogeneous discrete cases with anisotropic background:HOM23, HOM24, HOM25 and HOM33, HOM34, HOM35

This set of experiments is suggested to simulate the radiative transfer regime in the red and near infra-red spectral bands for homogeneous leaf canopies composed of a large number of non overlapping disc-shaped objects representing the foliage elements. These scatterers are located within a slab-like volume overlaying a NON-LAMBERTIAN horizontal plane standing for the underlying background condition (which could be snow, bare soil or understorey vegetation). 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 snow, bare soil and understorey vegetation conditions, respectively) is expressed with the parametric RPV model. Participants who wish to fit their own anisotropic background model to the RPV-simulated BRF data should inform the RAMI coordinators of this via the report files.

The foliage objects are randomly distributed finite size disc-shaped scatterers characterized by the specified radiative properties (reflectance, transmittance), and the orientation of the normals to the scatterers followed either an erectophile or a planophile distribution function. The particular values selected for the various input variables represent typical plant canopy conditions with bare soil, snow or green understorey as lower boundary condition (background).

The following figure exhibits a graphical representation of such a scene:

The tables below provide the details required to execute each of the experiments in this category. Every table is preceded by the corresponding experiment identifier tag <EXP> that is needed in the naming of the various measurement results files (see file naming and formatting conventions).

The first set of homogeneous discrete experiments refers to a vegetation canopy with a planophile leaf normal distribution and a scatterer radius of 0.05 m. An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a 25×25 m² canopy section can be found here. The file (is ~ 3.5 Mbytes and) contains 79577 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (to save it you have to select the central frame of the web browser before saving its content). A resume of some statistical properties of the content of this ASCII file can be seen here. In addition, the tables below provide an overview of the structural and spectral properties of these leaf canopies. Two spectral bands (red and NIR) and two illumination conditions (direct only with SZA=20° and 50°) are proposed for three different background anisotropy scenarios, referred to as HOM23, HOM24 and HOM25 in the tables below. The difference between experiments HOM23, HOM24 and HOM25 thus lies only in the BRF of the anisotropically scattering background (assumed to be reminiscent of snow, bare soil, and understorey vegetation). The background BRF is described by the three parameter of the RPV model.

Experiment identifier tag <EXP> : HOM23_DIS_PLA_RED_20 HOM24_DIS_PLA_RED_20 HOM25_DIS_PLA_RED_20
Solar Zenith Angle (SZA) 20 [deg] 20 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Planophile Planophile Planophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02
background BRF pattern
(RPV model parameters)
ρ0=0.075
k=0.55
Θ=−0.25
RPV simulated BRF data
ρ0=0.750
k=0.95
Θ=0.15
RPV simulated BRF data
ρ0=0.050
k=0.95
Θ=−0.10
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM23_DIS_PLA_NIR_20 HOM24_DIS_PLA_NIR_20 HOM25_DIS_PLA_NIR_20
Solar Zenith Angle (SZA) 20 [deg] 20 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Planophile Planophile Planophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44
background BRF pattern
(RPV model parameters)
ρ0=0.10
k=0.60
Θ=−0.20
RPV simulated BRF data
ρ0=0.70
k=0.95
Θ=0.10
RPV simulated BRF data
ρ0=0.15
k=0.80
Θ=−0.05
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM23_DIS_PLA_RED_50 HOM24_DIS_PLA_RED_50 HOM25_DIS_PLA_RED_50
Solar Zenith Angle (SZA) 50 [deg] 50 [deg] 50 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Planophile Planophile Planophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02
background BRF pattern
(RPV model parameters)
ρ0=0.075
k=0.55
Θ=−0.25
RPV simulated BRF data
ρ0=0.750
k=0.95
Θ=0.15
RPV simulated BRF data
ρ0=0.050
k=0.95
Θ=−0.10
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM23_DIS_PLA_NIR_50 HOM24_DIS_PLA_NIR_50 HOM25_DIS_PLA_NIR_50
Solar Zenith Angle (SZA) 50 [deg] 50 [deg] 50 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Planophile Planophile Planophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44
background BRF pattern
(RPV model parameters)
ρ0=0.10
k=0.60
Θ=−0.20
RPV simulated BRF data
ρ0=0.70
k=0.95
Θ=0.10
RPV simulated BRF data
ρ0=0.15
k=0.80
Θ=−0.05
RPV simulated BRF data

The next set of homogeneous discrete experiments refers to a vegetation canopy with a erectophile leaf normal distribution and a scatterer radius of 0.05 m. An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a 25×25 m² canopy section can be found here. The file is ~ 3.5 Mbytes and) contains 79577 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (to save it you have to select the central frame of the web browser before saving its content). A resume of some statistical properties of the content of this ASCII file can be seen here. In addition, the tables below provide an overview of the structural and spectral properties of these leaf canopies. Two spectral bands (red and NIR) and two illumination conditions (direct only with SZA=20° and 50°) are proposed for three different background anisotropy scenarios, referred to as HOM33, HOM34 and HOM35 in the tables below. The difference between experiments HOM33, HOM34 and HOM35 thus lies only in the BRF of the anisotropically scattering background (assumed to be reminiscent of snow, bare soil, and understorey vegetation). The background BRF is described by the three parameter of the RPV model.

Experiment identifier tag <EXP> : HOM33_DIS_ERE_RED_20 HOM34_DIS_ERE_RED_20 HOM35_DIS_ERE_RED_20
Solar Zenith Angle (SZA) 20 [deg] 20 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Erectophile Erectophile Erectophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02
background BRF pattern
(RPV model parameters)
ρ0=0.075
k=0.55
Θ=−0.25
RPV simulated BRF data
ρ0=0.750
k=0.95
Θ=0.15
RPV simulated BRF data
ρ0=0.050
k=0.95
Θ=−0.10
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM33_DIS_ERE_NIR_20 HOM34_DIS_ERE_NIR_20 HOM35_DIS_ERE_NIR_20
Solar Zenith Angle (SZA) 20 [deg] 20 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Erectophile Erectophile Erectophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44
background BRF pattern
(RPV model parameters)
ρ0=0.10
k=0.60
Θ=−0.20
RPV simulated BRF data
ρ0=0.70
k=0.95
Θ=0.10
RPV simulated BRF data
ρ0=0.15
k=0.80
Θ=−0.05
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM33_DIS_ERE_RED_50 HOM34_DIS_ERE_RED_50 HOM35_DIS_ERE_RED_50
Solar Zenith Angle (SZA) 50 [deg] 50 [deg] 50 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Erectophile Erectophile Erectophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02
background BRF pattern
(RPV model parameters)
ρ0=0.075
k=0.55
Θ=−0.25
RPV simulated BRF data
ρ0=0.750
k=0.95
Θ=0.15
RPV simulated BRF data
ρ0=0.050
k=0.95
Θ=−0.10
RPV simulated BRF data

Experiment identifier tag <EXP> : HOM33_DIS_ERE_NIR_50 HOM34_DIS_ERE_NIR_50 HOM35_DIS_ERE_NIR_50
Solar Zenith Angle (SZA) 50 [deg] 50 [deg] 50 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg]
Scatterer Radius 0.05 [m] 0.05 [m] 0.05 [m]
Leaf Area Index 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²] 1.0 [m² ⁄ m²]
Height of the canopy 1.0 [m] 1.0 [m] 1.0 [m]
Scatterer Normal Distribution Erectophile Erectophile Erectophile
Leaf scattering law Bi-Lambertian Bi-Lambertian Bi-Lambertian
Leaf scatterer reflectance 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44
background BRF pattern
(RPV model parameters)
ρ0=0.10
k=0.60
Θ=−0.20
RPV simulated BRF data
ρ0=0.70
k=0.95
Θ=0.10
RPV simulated BRF data
ρ0=0.15
k=0.80
Θ=−0.05
RPV simulated BRF data


Below is a list of the various measurements that are required for these test cases:


Prior to the performing of any RT model simulations, please refer to the 'definitions' pages for detailed instructions regarding the angular sign conventions for BRF simulations, as well as other RT model technicalities. Also read the relevant file naming and formatting conventions that must be adhered to by all participants. In addition, RAMI-IV offers participants the possibility to test the compliance of their model-generated results files with these file-naming and formatting convention, prior to their submission via ftp: To do so follow the on-line format checker link that appears in the top navigation bar during the active submission period.

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