This page provides descriptions of the architectural, spectral and illumination related properties of a 9 year old citrus orchard located in Wellington, South Africa (33°36′S 18°56′E).
The scene is based on data provided courtesy of Jan Stuckens, Ben Somers and colleagues (from the Katholieke Universiteit Leuven in Belgium) who carried out a detailed measurement campaign at this site in 2006/2007 and transferred their findings into a detailed 3D canopy architecture representation suitable for ingestion into RT models.
Thus, 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 can not be 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 of 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. This should facilitate the reconstruction of the citrus orchard canopy architecture as it is described on this page.
The Wellington Citrus Orchard scene is generated over an area of approximately 100×100 m² . The center of the coordinate system lies almost in the middle of the scene. The rows of the orchard fall along constant X-coordinate values (i.e., parallel to the Y axis) and are separated by approximatively 4.5 m. In a given row neighbouring trees are separated by approximatively 2.0 m. However, 11% of the potential tree positions are void due to missing trees. Overall, the architectural characteristics of the scene are thus as follows:
Scene dimensions:( X × Y × Z)
108.25 × 103.90 × 4.12 [m × m × m]
(Xmin, Ymin, Zmin)
−54.10, −51.95, 0.0 [m, m, m]
(Xmax, Ymax, Zmax)
54.10, 51.95, 4.12 [m, m, m]
Number of trees in scene
Leaf Area Index of scene
2.69126 [m² ⁄ m²]
Fractional scene coverage*
Inter-tree distance (within a row)
*The fractional cover is defined as 1 - direct transmission at zero solar zenith angle.
The table below provides the structural characteristics of the leaves (citrus sinensis L.) that feature within the Wellington Citrus Orchard. Indicated are average properties since the leaves within a single tree vary somewhat in their size and shape.
Average leaf length
8.8 cm ±1.9cm
Average leaf width
60 % of leaf length
mean one-sided foliage area
o: foliage curl in percent is defined as 100 times the length of the leaf divided by the circumference of a cylinder around which it is wrapped. E.g., 0% leaf curl mean - the leaf is flat - and the radius of the imaginary cylinder is infinite. 100% leaf curl mean - both ends of the leaf touch - and the radius of the cylinder around which the leaf is wrapped is equal to leaflength ⁄ 2 π.
The Wellington Citrus Orchard is generated on the basis of 10 individual tree representations of the citrus sinensis L. species. The table below provides an overview of some structural characteristics of these 10 tree representations. For those RT models capable of representing the 3D architecture of a given trees through a series of geometric primitives, the last three lines of each table contain links to data files with detailed specifications of the foliage and wood structural properties of the Wellington Citrus Orchard trees.
=: 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 normalised amount of foliage area having a normal in this zenith (or azimuth) angle range, and 3) the normalised amount 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 third-last row of each table column.
*: The graphs show the maximum radial distance of foliage elements in a given height interval plotted against the lower 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
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 Wellington Citrus Orchard is composed of 1115 individual trees. The following table indicates how these trees are distributed among the above tree classes and specifies the respective x,y locations of the tree centers of each tree class in the scene. The last row of each table contains an ASCII file with tree translation information for those RT models capable of ingesting the detailed 3D architecture of the tree models specified in the previous section.
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 datafiles (starting from 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 12 megabytes. It contains 30 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 80 Megabytes of storage.
Spectral canopy characteristics
Each one of the ten trees in the Wellington Citrus Orchard scene features distinct foliage spectral properties. All of the foliage, wood and background components in the Wellington Citrus Orchard scene feature LAMBERTIAN scattering properties. The tables below contains various spectral characteristics for nineteen different spectral bands. The experimental identifier for the Wellington Citrus Orchard scene is given by HET14_WCO_$$$_B**_## where $$$ relates to the solar azimuth angle, B** relates to the spectral bands (B01, B02, …, B19) and ## relates to the solar zenith angle. A text file that resumes all of the information in this table can be found here.
Five different illumination conditions are to be simulated for the Wellington Citrus Orchard.
More specifically the solar zenith angle (SZA) is 0, 20 or 50 degrees and the solar azimuth angle is equal to 0 or 90 degree. Only direct solar radiation is to be considered in these experiments.
The experimental identifier that is needed in the naming of the various measurement results files (see file naming and formatting conventions) for the Wellington Citrus Orchard scene is given by HET14_WCO_$$$_B**_## where $$$ relates to the solar azimuth angle, B** relates to the spectral bands (B01, B02, …, B19) and ## relates to the solar zenith angle.