This set of experiments was suggested to simulate the radiative transfer regime in the red and near infra-red spectral bands for spatially heterogeneous scenes resembling old growth coniferous forests in the absence of any underlying topography. As such this, test case features identical tree structures and spectral properties (also for the soil) as the "Gaussian hill coniferous forest" scenario, the only difference being the absence of topography.
More specifically, a large number of non-overlapping tree-like entities (composed of a conically shaped crown located above a cylindrical trunk) were randomly located across (and only partially covering) a planar surface that represented the underlying soil.
The finite sized foliage was randomly distributed within the conical volumes that represented the tree crowns, and was characterized by its specific radiative properties (reflectance, transmittance), and the orientation of its scatterer-normals (uniform distribution). The radiative properties of the underlying soil were specified (in this case a simple Lambertian scattering law) to reflect ideal winter conditions, ie. snowcover. To address the needs of different RT models, we are providing both a statistical scene description, as well as, a file with the exact spatial coordinates of every tree location (at the level of the soil). You may or may not make use of this information depending on the needs of your particular model.
The following figures exhibit a graphical representation of this scene:
The zero azimuth line was defined along the northern direction and coincides with the positive X-axis as indicated below:
The architecture of this scene contains tree-like entities that are composed of a conical crown on top of a cylindrical trunk. Note that these geometrical primitives do not overlap and that they remain the same for all trees that are populating the scene.
Within the scene the X,Y location of these tree-like entities is generated in a random manner (Poisson distribution). An ASCII file with the centre coordinates (Xc,Yc,Zc) of every tree in the scene (at the level of the underlying surface Zc=0) can be found here. This file (is ~ 0.24 Mbytes and) contains 10000 lines of format Xc Yc Zc and may serve as input to your scene creation process. Alternatively users may base their RT simulations on the following information regarding the overall characterisation of the scene architecture:
|Scene dimensions: ( ΔX × ΔY × ΔZ)||500.0 × 500.0 × 13.5 [m × m × m]|
|(Xmin, Ymin, Zmin)||−250.0, -250.0, 0.0 [m, m, m]|
|(Xmin, Ymax, Zmin)||−250.0, +250.0, 0.0 [m, m, m]|
|(Xmax, Ymin, Zmin)||+250.0, -250.0, 0.0 [m, m, m]|
|(Xmax, Ymax, Zmin)||+250.0, +250.0, 0.0 [m, m, m]|
|(Xmin, Ymin, Zmax)||−250.0, -250.0, 13.5 [m, m, m]|
|(Xmin, Ymax, Zmax)||−250.0, +250.0, 13.5[m, m, m]|
|(Xmax, Ymin, Zmax)||+250.0, -250.0, 13.5[m, m, m]|
|(Xmax, Ymax, Zmax)||+250.0, +250.0, 13.5[m, m, m]|
|Scatterer shape||Disc of negligible thickness|
|Scatterer radius||0.05 [m]|
|LAI of individual tree crown (cone)||5.0|
|Scatterer normal distribution in tree crown||Uniform|
|Number of trees in scene||10000|
|Spatial distribution of tree locations (X,Y) in scene||Random (Poisson Distribution)|
|Stem density [tree/hectare]||400|
|Fractional scene coverage of cones||0.4072|
|LAI of scene||2.0358|
|Tree crown height||12.0 [m]|
|Tree crown-base width||3.60 [m]|
|Tree trunk height||1.50 [m]|
|Tree trunk diameter||0.30 [m]|
The tables below provide the spectral properties and illumination details required to execute each of the experiments in this category.