Section 8.4 Reduction of the Geometric Data image quantization median cut algorithm • : • Figure 8.8 Median cut algorithm: (a) initial partitioning at the median regarding ж-values; (b) areas after a number of divisions with representatives (red panes) at the center of gravity of all points in a box (a) (b) At the beginning of the procedure, the number of areas is defined. After respectively many areas have been generated, the representative is positioned at the centroid of all the points in an area. In a plant population, the representative is thus assigned the attribute and thereby also the respective appearance resulting from the centroid element. Figure 8.8 demonstrates this process.
Chapters Hierarchical Instancing
Instancing can take place on several levels. Thus not only can different plants be represented over a single geometry, but instancing can also be implemented within tree structures: Leaf instancing is used to define a small branch; branch instancing is applied to define a larger branch, and so on. This way, optimal compression is achieved for the geometry of a tree.
The concept can be extended in that for each instancing object several representatives are generated to increase the variability of the total geometry. This step was applied in  in order to simplify an image-based rendering method.