of $30 \textrm{m} \times 30 \textrm{m}$. In Fig \[fig:forestExample\], a detail is shown of a $30$m pixel, for the forest consisting of 60$\%$ beech trees and 40$\%$ poplars. Note here that the spatial resolution of the forest scene is significantly larger than the resolution of the orchard scene detailed in paragraph \[sec:orchard\]. These choices allow different plant production systems to be covered, with various species combinations, sets of endmembers and spatial resolution scales.

![High resolution detail of a $30$m pixel of the forest with 60$\%$ beech trees and 40$\%$ poplars.[]{data-label="fig:forestExample"}](forest_detail.\figextension){width="0.75\columnwidth"}

In-situ measurement {#sec:in situ}
-------------------

In addition, an experiment was conducted in the same orchard used for the calibration of the virtual orchard described in paragraph \[sec:orchard\]. Significant weed cover, dominantly *Lolium sp. L.* ($\approx30\%$ of the inter-row spacing, concentrated in dense patches) was present. Throughout the orchard, in-situ measured reflectance spectra of $60$ mixed ground plots were collected, i.e., $25$ mixtures of tree and soil, $25$ mixtures of tree and weed, and $25$ mixtures of tree, soil and weed. Reflectance measurements were performed in August using a spectroradiometer with a $25^{\circ}$ fore-optic, covering the $350-2500$nm spectral domain (Analytic Spectral Devices, Boulder, USA). The measurements were taken from nadir at 