## 2 Materials and Methods
### Data Collection  
Various terrestrial measurements were conducted in the field, primarily involving the collection of ground control points (GCPs) and reference measurements for the subsequent validation of the analysis results. The reference measurements include vine height measures and the measurement of vine stem locations. The primary device employed for point data collection was the Leica Viva GS16 GNSS Rover (Leica Geosystems, St. Gallen, Switzerland). Eight GCPs were measured with this rover. This process was integral in georeferencing the results of photogrammetric processing, ultimately enabling their transformation into a projected coordinate system, specifically the ETRS89/Austria Lambert (EPSG-3416). The GCPs were installed across the entire study site, encompassing varying topographic levels, including locations both above and below steep slopes. Due to the foliage cover of the vines and to the plants' developmental stages, different UAS missions were necessary in order to derive the desired data. The usage of the different datasets is described in the methodological part of this manuscript. RGB and multispectral data were collected in the field. Different flight altitudes were tested in order to achieve ground sample distances (GSD) close to 1 cm. The flight angle of the UAS varied from full nadir to 45\({}^{\circ}\) oblique in order to scan the sidewalls of the vines. For UAS data collection, an automated flight plan was used with a forward image overlap of 80% and a side overlap of 90%.  
Figure 2 displays the camera positions alongside the 3D point cloud, generated following the completion of photogrammetric processing steps. The first UAS mission was conducted in April of 2023, when the plants had not developed full leaf coverage, being in the phenological stage EL 1-3 following the Modified EL system [18]. The absence of foliage made it possible to photogrammetrically record the stems of the individual vine plants, which was important for derivation of the stem positions in a later step. For the first flight, the DJI M600 (DJI, Shenzhen, China) was used, equipped with a Sony A7 iii camera with 42.4 megapixels and a Sony 50 mm f1.8 lens (Sony Corporation, Tokyo, Japan). The second flight was conducted in September 2023, when the vines were in phenology stage EL 38, 1 h before the grapes were harvested. Here, the foliage was in its final pruning stage [18]. The data from the second flight were used to derive the ecosystem structures of the plants (LSA, LAI, and vine height). For the second flight, the same UAS was used as for the first flight, but a multispectral data set was also recorded in order to be able to base the derivation of the vine plants on their spectral signature. The multispectral sensor used was the Micasense Dual (Micasense Inc., Seattle, WA, USA). The Micasense is capable of  
Figure 1: Study area in Carinthia showing seven blocks of wine grapes across the 0.7 ha parcel.  
recording 10 spectral bands with a spatial resolution of 7 cm. Before and after each flight, the Micasense Dual was calibrated using the reference images provided with the sensor [19]. For both flights, a cross-grid pattern was used and supplemented with oblique flights. The flight altitude of the UAS was 30 m for oblique flights and 50 m for the nadir cross-grid. The automated flight plan was executed automatically, with the terrain following an underlying digital elevation model (DEM).