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17-May-2022   
Path: RAMI-IV : EXPERIMENTS : ABSTRACT CANOPIES : HETEROGENEOUS : CONSTANT SLOPE
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Abstract heterogeneous canopies with a constant slope:HET23, HET24 and HET33, HET34

This set of experiments is suggested to simulate the radiative transfer regime in the red and near infra-red spectral bands for heterogeneous leaf canopies situated on an incline of constant slope. For energy conservation purposes the abstract tree crowns are inclined and the background is kept horizontal rather than having a background that is sloping and trees that are upright. The canopy is thus represented by a large number of identical, non-overlapping and inclinded cylindrical objects that are located over and only partially covering a horizontal plane standing for the underlying background.
Each individual cylinder contains a 'cloud' of oriented finite-sized disc-shaped scatterers representing the foliage. These Bi-Lambertian foliage elements are characterized by specified radiative properties (reflectance, transmittance) defined separately for both the visible and near-infrared spectral domains. The orientation of the normals of the foliage elements (scatterers) follows a uniform (or what is sometimes called a spherical) distribution function, i.e., the probability to be intercepted by a leaf is independent of the direction of travel of the radiation (see the definitions page). The background surface follows a Lambertian scattering laws.

The following figures exhibit graphical representations of the 4 constant slope heterogeneous canopy scenarios:

HET23 & HET24 (15° inclination) HET33 & HET34 (30° inclination)

As can be seen in the image below, the cylindrical objects (when placed upright) have a height of 3.0 m, a radius of 1.0 m, and a leaf area index of 4.05 m² ⁄ m². Two different inclinations of the cylinders are envisaged: 15 degree and 30 degree, respectively. These inclinations can be obtained by rotating the cylinder (centered at the origin 0,0,0 ) along the Y axis such that the positive Z axis moves towards the positive X axis. In the canopy the cylindrical objects have their center coordinates located between heigths of 2.0099 m and 2.0101 m. Overall two different canopy densities, two different slopes (i.e., cylinder inclinations) and four different illumination conditions will be presented. To address the needs of different RT models, both a statistical scene description, as well as ASCII files with the exact coordinates of the scatterers and the cylinder locations in the scene are provided.

Sparse heterogeneous canopy with a constant slope of 15 degree:

The table below provides the details required to build and run a RT model on the sparse heterogeneous cylinder canopy with a constant inclination of 15 degree. Also indicated are the X and Y axes with the azimuth angle counting scheme.

experiment HET23
( X × Y × Z) [m × m × m] 101.30 × 101.0 × 3.58
(Xmin, Ymin, Zmin) [m, m, m] −50.65, −50.5, 0.0
(Xmax, Ymax, Zmax) [m, m, m] +50.65, +50.5, 3.58
Scatterer shape Disc of negligible thickness
Scatterer radius [m] 0.0075
Foliage scattering law Bi-Lambertian
LAI of individual (upright) cylinder 4.05
radius of cylinder [m] 0.5
height of (upright) cylinder [m] 3.0
cylinder center height range [m] 2.0099 - 2.0101
Scatterer normal distribution Uniform
Number of cylinders 1274
LAI of scene 0.396058
Background scattering law Lambertian

An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a cylindrical volume (centered at 0,0,0 but inclined via a 15 degree rotating around the Y axis such that the positive z axis moves towards the positive X axis) is available here. This files (are ~ 1.2 Mbytes and) contain 17999 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (provided that you are able to create multiple instances of its content, each one of which is then translated to the actual locations of the cylinder centers in the scene. An ASCII file with the X, Y, Z cylinder center coordinates can be found here.

The table below provides detailed information regarding the illumination conditions and spectral properties of the foliage and background constituents of the sparse canopy scenarios. The table is preceeded 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). Two spectral bands (red and NIR) and four illumination conditions (direct only with SZA=20° and 50° for solar azimuths of 0° and 180°) are proposed.

Experiment identifier tag <EXP> : HET23_DIS_000_RED_35 HET23_DIS_000_RED_65 HET23_DIS_180_RED_05 HET23_DIS_180_RED_35
Solar Zenith Angle (SZA) 35 [deg] 65 [deg] 5 [deg] 35 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 180 [deg] 180 [deg]
Leaf scatterer reflectance 0.06 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02 0.02
background reflectance
0.13 0.13 0.13 0.13

Experiment identifier tag <EXP> : HET23_DIS_000_NIR_35 HET23_DIS_000_NIR_65 HET23_DIS_180_NIR_05 HET23_DIS_180_NIR_35
Solar Zenith Angle (SZA) 35 [deg] 65 [deg] 5 [deg] 35 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 180 [deg] 180 [deg]
Leaf scatterer reflectance 0.50 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44 0.44
background reflectance
0.16 0.16 0.16 0.16

Dense heterogeneous canopy with a constant slope of 15 degree:

The table below provides the details required to build and run a RT model on the dense heterogeneous cylinder canopy with a constant inclination of 15 degree. Also indicated are the X and Y axes with the azimuth angle counting scheme.

experiment HET24
( X × Y × Z) [m × m × m] 101.30 × 101.0 × 3.58
(Xmin, Ymin, Zmin) [m, m, m] −50.65, −50.5, 0.0
(Xmax, Ymax, Zmax) [m, m, m] +50.65, +50.5, 3.58
Scatterer shape Disc of negligible thickness
Scatterer radius [m] 0.0075
Foliage scattering law Bi-Lambertian
LAI of individual (upright) cylinder 4.05
radius of cylinder [m] 0.5
height of (upright) cylinder [m] 3.0
cylinder center height range [m] 2.0099 - 2.0101
Scatterer normal distribution Uniform
Number of cylinders 5093
LAI of scene 1.58330
Background scattering law Lambertian

An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a cylindrical volume (centered at 0,0,0 but inclined via a 15 degree rotating around the Y axis such that the positive z axis moves towards the positive X axis) is available here. This files (are ~ 1.2 Mbytes and) contain 17999 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (provided that you are able to create multiple instances of its content, each one of which is then translated to the actual locations of the cylinder centers in the scene. An ASCII file with the X, Y, Z cylinder center coordinates can be found here.

The table below provides detailed information regarding the illumination conditions and spectral properties of the foliage and background constituents of the sparse canopy scenarios. The table is preceeded 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). Two spectral bands (red and NIR) and four illumination conditions (direct only with SZA=20° and 50° for solar azimuths of 0° and 180°) are proposed.

Experiment identifier tag <EXP> : HET24_DIS_000_RED_35 HET24_DIS_000_RED_65 HET24_DIS_180_RED_05 HET24_DIS_180_RED_35
Solar Zenith Angle (SZA) 35 [deg] 65 [deg] 5 [deg] 35 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 180 [deg] 180 [deg]
Leaf scatterer reflectance 0.06 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02 0.02
background reflectance
0.13 0.13 0.13 0.13

Experiment identifier tag <EXP> : HET24_DIS_000_NIR_35 HET24_DIS_000_NIR_65 HET24_DIS_180_NIR_05 HET24_DIS_180_NIR_35
Solar Zenith Angle (SZA) 35 [deg] 65 [deg] 5 [deg] 35 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 180 [deg] 180 [deg]
Leaf scatterer reflectance 0.50 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44 0.44
background reflectance
0.16 0.16 0.16 0.16

Sparse heterogeneous canopy with a constant slope of 30 degree:

The table below provides the details required to build and run a RT model on the sparse heterogeneous cylinder canopy with a constant inclination of 30 degree. Also indicated are the X and Y axes with the azimuth angle counting scheme.

experiment HET33
( X × Y × Z) [m × m × m] 101.30 × 101.0 × 3.54
(Xmin, Ymin, Zmin) [m, m, m] −50.65, −50.5, 0.0
(Xmax, Ymax, Zmax) [m, m, m] +50.65, +50.5, 3.58
Scatterer shape Disc of negligible thickness
Scatterer radius [m] 0.0075
Foliage scattering law Bi-Lambertian
LAI of individual (upright) cylinder 4.05
radius of cylinder [m] 0.5
height of (upright) cylinder [m] 3.0
cylinder center height range [m] 2.0099 - 2.0101
Scatterer normal distribution Uniform
Number of cylinders 1274
LAI of scene 0.396058
Background scattering law Lambertian

An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a cylindrical volume (centered at 0,0,0 but inclined via a 30 degree rotating around the Y axis such that the positive z axis moves towards the positive X axis) is available here. This files (are ~ 1.2 Mbytes and) contain 17999 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (provided that you are able to create multiple instances of its content, each one of which is then translated to the actual locations of the cylinder centers in the scene. An ASCII file with the X, Y, Z cylinder center coordinates can be found here.

The table below provides detailed information regarding the illumination conditions and spectral properties of the foliage and background constituents of the sparse canopy scenarios. The table is preceeded 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). Two spectral bands (red and NIR) and four illumination conditions (direct only with SZA=20° and 50° for solar azimuths of 0° and 180°) are proposed.

Experiment identifier tag <EXP> : HET33_DIS_000_RED_50 HET33_DIS_000_RED_80 HET33_DIS_000_RED_10 HET33_DIS_180_RED_20
Solar Zenith Angle (SZA) 50 [deg] 80 [deg] 10 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg] 180 [deg]
Leaf scatterer reflectance 0.06 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02 0.02
background reflectance
0.13 0.13 0.13 0.13

Experiment identifier tag <EXP> : HET33_DIS_000_NIR_50 HET33_DIS_000_NIR_80 HET33_DIS_000_NIR_10 HET33_DIS_180_NIR_20
Solar Zenith Angle (SZA) 50 [deg] 80 [deg] 10 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg] 180 [deg]
Leaf scatterer reflectance 0.50 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44 0.44
background reflectance
0.16 0.16 0.16 0.16

Dense heterogeneous canopy with a constant slope of 30 degree:

The table below provides the details required to build and run a RT model on the dense heterogeneous cylinder canopy with a constant inclination of 30 degree. Also indicated are the X and Y axes with the azimuth angle counting scheme.

experiment HET34
( X × Y × Z) [m × m × m] 101.30 × 101.0 × 3.54
(Xmin, Ymin, Zmin) [m, m, m] −50.65, −50.5, 0.0
(Xmax, Ymax, Zmax) [m, m, m] +50.65, +50.5, 3.58
Scatterer shape Disc of negligible thickness
Scatterer radius [m] 0.0075
Foliage scattering law Bi-Lambertian
LAI of individual (upright) cylinder 4.05
radius of cylinder [m] 0.5
height of (upright) cylinder [m] 3.0
cylinder center height range [m] 2.0099 - 2.0101
Scatterer normal distribution Uniform
Number of cylinders 5093
LAI of scene 1.58330
Background scattering law Lambertian

An ASCII file with the radius (R), centre coordinates (Xc,Yc,Zc), and direction cosines (Dx,Dy,Dz) of every single leaf in a cylindrical volume (centered at 0,0,0 but inclined via a 30 degree rotating around the Y axis such that the positive z axis moves towards the positive X axis) is available here. This files (are ~ 1.2 Mbytes and) contain 17999 lines of format R Xc Yc Zc Dx Dy Dz that may serve as input to your scene creation process (provided that you are able to create multiple instances of its content, each one of which is then translated to the actual locations of the cylinder centers in the scene. An ASCII file with the X, Y, Z cylinder center coordinates can be found here.

The table below provides detailed information regarding the illumination conditions and spectral properties of the foliage and background constituents of the sparse canopy scenarios. The table is preceeded 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). Two spectral bands (red and NIR) and four illumination conditions (direct only with SZA=20° and 50° for solar azimuths of 0° and 180°) are proposed.

Experiment identifier tag <EXP> : HET34_DIS_000_RED_50 HET34_DIS_000_RED_80 HET34_DIS_000_RED_10 HET34_DIS_180_RED_20
Solar Zenith Angle (SZA) 50 [deg] 80 [deg] 10 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg] 180 [deg]
Leaf scatterer reflectance 0.06 0.06 0.06 0.06
Leaf scatterer transmittance 0.02 0.02 0.02 0.02
background reflectance
0.13 0.13 0.13 0.13

Experiment identifier tag <EXP> : HET34_DIS_000_NIR_50 HET34_DIS_000_NIR_80 HET34_DIS_000_NIR_10 HET34_DIS_180_NIR_20
Solar Zenith Angle (SZA) 50 [deg] 80 [deg] 10 [deg] 20 [deg]
Solar Azimuth Angle (SAA) 0 [deg] 0 [deg] 0 [deg] 180 [deg]
Leaf scatterer reflectance 0.50 0.50 0.50 0.50
Leaf scatterer transmittance 0.44 0.44 0.44 0.44
background reflectance
0.16 0.16 0.16 0.16


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

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