weeds. []{data-label="fig:orchardExample"}](Orchard_weeds "fig:"){width="\columnwidth"}

### Forest scene {#sec:forest}

The virtual forest consisted of a soil background planted with trees selected from the species-specific tree pools. More precisely, to simulate the forest scene, $3$D tree geometry descriptions were available for beech (*Fagus sylvatica* L.) and poplar (*Populus nigra* L. var. *“italica”* Muench). Each tree was characterized by a specific structure based on its age (i.e., $20$ years old). All leaves were assigned a species-specific reflectance and transmittance spectrum extracted from the leaf optical properties experiment (LOPEX) dataset [@Hosgood1995]. Examples of the soil, beech and pop endmember signatures are depicted in Fig \[fig:forest\_endmembers\].

![Forest synthetic dataset. Example of the generated endmember spectra: soil (black), beech (red) and pop (green).[]{data-label="fig:forest_endmembers"}](endmembers_forest_one_instance.pdf){width="0.75\columnwidth"}

To achieve a nearly $100\%$ canopy cover, the average tree spacing has been set to $5$m for the beech trees and $1$m for the poplars. A series of six forest scenes has been rendered providing a gradual transition from a forest scene completely dominated by one species to a scene dominated by the other species. More precisely, $20\%$ of the beech trees have been randomly replaced by poplar trees in the subsequent scene. Each forest scene consisted of $15\times15$ pixels, with a pixel size 