# Visibility Assessment of New Photovoltaic Power Plants in Areas with Special Landscape Value
## 3 Case Study  
We have applied the proposed methodology to the region of La Rioja in northern Spain. Specifically, the selected area of study corresponds to the area crossed by the Way of St. James. Figure 3 shows, in the bottom right corner, the region of La Rioja, and the studied area. The Way of Saint James is a world-renowned pilgrimage route that runs through northern Spain, from the western range of the Pyrenees to the city of Santiago de Compostela, in the northwest of the country. In 1993 it was declared a World Heritage Site by UNESCO, forming part of the cultural legacy of Europe, one of the most varied in the world [42].  
In the studied area, the Way of St. James does not have a single route, rather it has different variants or branches that run through different towns and places with great cultural richness close to the main route and where it is possible to visit sanctuaries, temples and other monuments that are part of the cultural heritage of the region. The main route crossing La Rioja was established at the beginning of the 11 th century. In addition to the historical and cultural interest of the Way, the different routes in La Rioja cross through vineyards that constitute an environment of special landscape beauty. The five routes of the Way in La Rioja are shown in Figure 3 and these are: main route, route of San Millan, route of Ciruena, route of Haro, and route of Brinas.  
In this work, the possible potential observers correspond to pilgrims walking along each of the five routes, while the inhabitants of the urban centres, included in the study area, have not been considered. Data related to pilgrimages have been taken from periodic statistical reports published by the Pilgrim's Office in the city of Santiago de Compostela. For this work, data referring to pilgrimages during the year 2019 have been used [43]. In that year, about 190,000 pilgrims walked these routes of the Way.  
A PV system with a two-axis tracker has been selected for the construction of new PV plants in this case study. Each system can support up to 10 kW of power, depending on the type of PV module installed. The height of such a tracker is not constant throughout the day and its value varies depending on the elevation angle of the sun (angle between the sun's rays and the horizontal plane). The maximum height \(H_{pv}\) that can be reached by this facility is 6 m above the ground, mainly in the early and late hours of the day. This height was selected for this study because it is the most unfavourable value from the visibility criterion. The area occupied by a single tracker is approximately 625 m\({}^{2}\), including the terrain corresponding to transit areas.  
In the GIS tool the main input data are the DSM and the DTM of the area of study. According to data from the National Geographic Institute of Spain [44], the DSM was obtained from flights made during the summer of 2016. This geographic data is composed of a set of square cells with an initial size of 2.5 \(\times\) 2.5 m. Using resampling techniques, the original DSM was converted to a DSM with a cell size of 25 \(\times\) 25 m. We used the nearest neighbour interpolation as the resampling method, which is one of the fastest interpolation methods. With this method, each cell or pixel of the resampled raster data acquires the same value as its nearest neighbour in the original raster. Originally, the DTM had a cell size of 25 \(\times\) 25 m; therefore, it was not necessary to apply sampling techniques. The final cell size was chosen according to the size occupied by a two-axis solar tracker with a capacity of 10 kW. In other words, each solar tracker would occupy the geographic area represented by a single cell in GIS.