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Ofenpass Pine Stand (Winter)

RAMI IV phase

This page provides descriptions of the architectural, spectral and illumination related properties of a mountain pine (Pinus montana) stand located in the eastern Ofenpass valley of Switzerland. The forest stand features trees aged between 90 and 200 years and has been without management since 1914. The Ofenpass pine stand description provided below is based on inventory data gathered by the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), as well as, field and Lidar data acquired and processed by Felix Morsdorf, Ben Kötz and colleagues from the Remote Sensing Laboratories (RSL) of the University of Zurich, Switzerland. Potential RAMI participants are to treat the information presented on this page as actual 'inventory data', that is, they should identify/extract those parameters and characteristics that are required as input to their canopy reflectance models.

In some cases this may mean that simplifications have to be made to the available information, or, that parts of the available information cannot be - or have to be modified before being - exploited with a given radiative transfer model. Whatever the case may be, all potential RAMI participants should mimic the standard practices that they use when matching actual field measurements to the required set(s) of input parameters for their model(s). If this means that you need more information than provided, please do not hesitate in contacting us. Last but not least, for those 3D models capable of maintaining architectural fidelity down to the individual shoot and branch level a series of ASCII (text) files containing the Cartesian coordinates of various geometric primitives (triangles, spheres and cylinders) and their transformations will be given.

Ofenpass Pine Stand (Winter)
Ofenpass Pine Stand (Winter) scene description.
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Ofenpass Pine Stand (Winter) scene description
Ofenpass Pine Stand (Winter) scene description.
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Ofenpass Pine Stand (Winter) scene description
Ofenpass Pine Stand (Winter) scene description.
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The Ofenpass Mountain Pine forest inventory was carried out over a large area from which a 100×100 m² subplot was selected for RAMI. The origin of the coordinate system was placed at the south-western end of this area. However, in order to include the tree crowns of those trees that were located within the 1 hectare area of the RAMI Mountain Pine Winter stand representation it was necessary to expand the scene area slightly beyond the one hectare. Maintaining the origin of the tree location coordinate system thus resulted in some negative x,y values in the table below. Overall architectural characteristics of the scene are thus as follows:

Scene dimensions:( X × Y × Z)103.1214 × 103.2308 × 15.0213 [m × m × m]
(Xmin, Ymin, Zmin)−1.6521, −1.9206, 0.0 [m, m, m]
(Xmax, Ymax, Zmax)101.4693, 101.3102, 15.0213 [m, m, m]
Number of trees in scene991 (621 live, 120 dead, 250 understorey)
Leaf Area Index of scene*0.744870
Fractional scene coverage**0.1248

*The LAI of the pine trees is computed using half the total area of the needles in a shoot.

**The fractional cover is defined as 1 - direct transmission at zero solar zenith angle.

The table below provides the architectural characteristics of the shoots of the trees used in the Ofenpass Pine stand representation. Individual shoots are generated by stacking four sub-shoots - with architectures based on the geometry proposed by Smolander et al., 2003 (RSE) - on top of each other. RT models capable of representing the architecture of individual foliage elements with a series of geometric primitives (triangle, sphere, cylinder) may want to use the information provided in the ASCII (text) files accessible from the last row in each table below.

Mountain pine shoot leaf description
Mountain pine shoot leaf description.
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Number of needles240
total needle area*224.614 cm²
needle lengtho2.8 and 4.5 cm
needle diameter0.05 cm
angle between twig and needleo30° and 40°
fascicle angle0 - 27.7°
twig length9.0 cm
twig diameter0.5 cm
structural description file (geometric primitives)click here

*: this total needle area value arises if the needles are represented as elongated spheres (as is the case in the ASCII file accessible via the link in the last row of the above table). If individual needles are represented as cylinders (with discs as endcaps) then the total needle area of the shoot is different and the number of shoots per mountain pine tree should be adjusted accordingly.

o: for a detailed description of the shoot structure please read the header of the structural description file accessible via the link in the last row of this table.

The Ofenpass Mountain Pine forest is generated on the basis of 13 individual tree representations. Twelve of these pertain to live Mountain pine (Pinus Montana) trees and one refers to a dead Mountain pine tree representation. The latter is due to the fact that about 20% of the overall tree density is made up of dead (standing) trees. The table below provides an overview of some structural characteristics of these various tree representations. For those RT models capable of representing the 3D architecture of a given trees in a voxelised manner, or alternatively, through a series of geometric primitives the last four lines of this table contain links to data files with detailed specifications of the foliage and wood structural properties of the Ofenpass Mountain Pine forest (Winter) trees.

tree identifierPIMO1PIMO2PIMO3PIMO4PIMO5PIMO6PIMO7PIMO8PIMO9PIMO10PIMO11PIMO12PIMO13PIMO14
tree height [m]3.245.996.518.849.0811.0110.6113.6013.0712.3914.6515.1210.021.09
diameter at breast height (DBH) [cm]8.011.012.415.413.416.824.4 32.434.634.436.025.622.6NA
Foliage normal distribution: zenith angle= graph
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Foliage normal distribution: azimuth angle=graph
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height to live/green crown [m]0.321.432.063.224.774.967.382.827.6710.238.8110.32NA0.12
crown radiusx mean [m] 0.27 0.23 0.46 0.42 0.25 0.57 0.38 0.60 0.33 0.27 0.54 0.36 0.14 0.17
maximum [m] 0.94 1.02 1.34 1.15 1.03 1.70 1.18 1.77 1.18 1.08 1.70 1.20 0.77 0.43
picture picture picture picture picture picture picture picture picture picture picture picture picture picture picture
vertical profile of crown radii* [m]graph
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half-total foliage area of tree [m²]# 17.08194.0879823.191417.63224.570914.39785.4244320.12546.74972.212455.70054.35750.05.89612
vertical profile of leaf area° [m]graph
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total wood area of tree [m²]2.11752.534445.969515.841874.83909.9318611.558220.070212.687211.322719.739512.93585.541470.32731
vertical profile of wood area° [m²]graph
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tree shape image Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter) Ofenpass Pine Stand (Winter)
foliage structure (triangle mesh) file file file file file file file file file file file file NA file
wood structure (triangle mesh) file file file file file file file file file file file file file file

=: the zenith angle of the foliage normal is defined as the angle between the vertical and the normal of the main twig of the shoot (for a shoot axis aligned along the z-axis the normal was arbitrarily chosen to lie along the y-axis). Rather than spanning the full range of possible zenith angles (i.e., from 0 to 180 degree) as could be expected for non-flat asymmetric objects, it was chosen to follow the convention of foliage normals pointing only into the upper hemisphere. This is because RAMI participants, that make use of this foliage normal distribution information, will in all likelihood have models where scatterers are represented as flat (disc or equilateral triangle shaped) objects. However, should your model require a description of the foliage normal zenith angle distribution up to 180 degrees then please do not hesitate in contacting us and we will provide this information to you. For both the zenith and azimuth angle distributions the 'graph' link shows an image of the normalised foliage normal distribution versus zenith (or azimuth) angle of the foliage normal. The 'data' files for the zenith and azimuth angle distribution have three columns indicating 1) the upper value of the zenith (or azimuth) angle in a given bin, 2) the fraction of foliage area having a normal in this zenith (or azimuth) angle range, and 3) the fraction of wood area having a normal that falls in this zenith (or azimuth) angle range. Bin angle widths were chosen to be 5 degrees and 10 degrees for zenith and azimuth angles, respectively.

x: the crown radius of actual trees is varying with azimuth angle. This can be seen in the various pictures showing a perspective-free nadir view of a given tree located at x=0,y=0 (concentric circles indicate the distance from the origin in steps of 0.25m). The mean and maximum values were computed from the triangle objects making up the 3D trees depicted in the picture in the the fourth-last row of each table column.

*: the graphs show the maximum radial distance of foliage elements in a given height interval plotted against the upper height level of that height interval. The data files have five columns: lower-height-of-bin-in-units-of-meters upper-height-of-bin-in-units-of-meters minimum_radial-distance_of_foliage-in-units-of-m maximum_radial-distance_of_foliage-in-units-of-m. mean_radial-distance_of_foliage-in-units-of-m

#: this value corresponds to the one-sided leaf area for flat leaves. For Mountain pine trees it corresponds to the sum of the (maximum) silhouettes of all the individual needles in the tree (i.e., half the total needle area per tree).

o: the data files have 3 columns: lower-height-of-bin-in-units-of-meters upper-height-of-bin-in-units-of-meters area-of-wood-or-foliage-in-units-of-m2.

The Ofenpass Mountain Pine forest is composed of 991 individual trees. The following table indicates how these trees are distributed among the above tree classes and specifies their respective x,y locations of the tree centers of each tree class in the forest stand. The last row of this table contains an ASCII file with tree rotation and translation information for those RT models capable of ingesting the detailed 3D architecture of the tree models specified in the previous section.

TABLE 1:

tree identifierPIMO1PIMO2PIMO3PIMO4PIMO5PIMO6PIMO7PIMO8PIMO9PIMO10PIMO11PIMO12PIMO13PIMO14
tree number per class15364332505910329131602538120250
x,y coordinates of tree centers [m,m] data data data data data data data data data data data data data data
tree rotations and translation (ASCII file)x data data data data data data data data data data data data data data

x: these files contain pseudo code to rotate individual trees around their z axis and translate them from the origin to the x,y locations specified in the data files of the previous row of this table. Positive rotation angles in these files indicate that when looking down from the positive Z axis towards the origin of the coordinate system a counterclockwise rotation will result in moving the positive x axis towards the positive y axis. The angle of rotation is in the 7th column of these data files (starting the count from 1).


RAMI participants with 3D RT models capable of representing objects using geometric primitives can download a single compressed ZIP archive with all the tree architectural ASCII information that is listed in the above tables by clicking HERE. Note: The size of the compressed archive is about 1.8 megabytes. It contains 42 ASCII files and can be unzipped using 'WINZIP' on windows or 'unzip' on linux/unix operating systems. Beware that the inflated archive will take up 9.7 Megabytes of storage.

The Figure below shows the tree locations for the Ofenpass Mountain pine (Winter) stand. Crown of live trees are open circles. Red dots are trees belonging to the (randomly dispersed) understorey. Black dots are (randomly dispersed) dead trees. The origin of the coordinate system is in the lower left hand side corner of the image.
The Figure below shows the tree locations for the Ofenpass Mountain pine (Winter) stand. Crown of live trees are open circles. Red dots are trees belonging to the (randomly dispersed) understorey. Black dots are (randomly dispersed) dead trees. The origin of the coordinate system is in the lower left hand side corner of the image.
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Only the foliage and woody components in the Ofenpass pine stand (Winter) scene feature LAMBERTIAN scattering properties. The background properties on the other hand are NON-LAMBERTIAN. To capture the directional variability of the hemispherical directional reflectance factor (HDRF) of snow, the RPV model has been fitted to a series of actual goniometer observations. The tables below contains the magnitudes of the reflectance and transmission characteristics of the various canopy components for nineteen different spectral bands as well as the RPV parameters describing the anisotropy of the background HDRF. The experimental identifier for the Ofenpass Pine Stand (Winter) scene is given by HET08_OPS_WIN_B**_47 where B** relates to the spectral bands (B01, B02, …, B19). An ASCII (text) file that resumes all of this information can be found here.

The illumination conditions for the Ofenpass Mountain Pine forest stand feature both direct and isotropic diffuse components. Direct solar light is characterised by a solar zenith angle (SZA) of 47.0 degree and a solar azimuth angle equal to 151.3 degree. The table below indicates the ratio of isotropic diffuse to total incident radiation for the nineteen different spectral bands.

The figure below shows a perspective-free view of the Ofenpass Mountain pine stand with the Cartesian coordinate system and the direction of the incident solar radiation (blue arrow) superimposed. <strong>Azimuth angles are counted in an anti-clockwise direction from the positive X-axis towards the positive Y-axis</strong> as indicated by the (dotted blue) arc around the origin.
The figure below shows a perspective-free view of the Ofenpass Mountain pine stand with the Cartesian coordinate system and the direction of the incident solar radiation (blue arrow) superimposed. Azimuth angles are counted in an anti-clockwise direction from the positive X-axis towards the positive Y-axis as indicated by the (dotted blue) arc around the origin.
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