Integrated Airborne Lidar-UAV Methods For Archaelogical Mapping In Vegetation-Covered Areas

The significance of 3D digitization in Cultural Heritage conservation processes is nowadays becoming more and more relevant. Certainly, preserving the landscape and archaeological heritage increasingly depends on the strategies in place to document, manage and analyse data and foresee possible valorization opportunities. As well as the archaeological sites to which they lead, the hiking trails are of particular importance for the landscape context stratification to which they belong. The network of trails within an park area or archaeological site, such as the one to which this research refers, assumes significance both as a way of access to the site and as a cultural element itself, resulting from multiple stratifications that have evolved during history and representing historical traces of connection between settlements. Thanks to the evolution of geospatial science and remote sensing technologies for surveying and automation in data processing, multi-sensor terrestrial and aerial methods are nowadays available in research and applications for 3D mapping in a geographical scale perspective with dense and accurate digital surface models (DSM). In the last decades, LiDaR airborne data processing and applications have been widely studied (Maas & Vosselman, 2010; Z. Chen et al., 2017), as well as the applications for archaeological study purposes of Digital Elevation Models (DEM) derived from LiDaR airborne point clouds (Mazzacca et al., 2022). If we consider that these approaches are already consolidated for airborne DSM data, the research is also orienting toward UAV DSM, both from newer LiDaR equipment solutions and photogrammetric DSM (Spanò et al., 2018). Due to high resolution technologies, it's possible to enhance the built Heritage site knowledge and simultaneously monitor the morphological and micro-topographic aspects of the territorial context. The flexibility of the 3D GIS multiscale databases manages to operate in different built and natural heritage contexts and also to monitor the conservation status of vegetation and other natural components of the territorial context, such as water and soil shapes. In fact, structuring a 3D geospatial database in a GIS environment, where both already structured and acquired data are integrated and continuously updated, allows multiple possibilities not only for data visualisation and archiving, but mainly for geographical data correlation and supporting interpretation. Developing territorial analyses can return products that can be further treated to semantically label entire territory layers (Chen et al., 2016), especially with the help of regional/urban digital cartography and survey data acquired in the field. On the other hand, obtaining an overall multiscale model - resulting from the integration and harmonisation of multisensory 3D data, both airborne and terrestrial originated - allows a flexible monitoring tool, due to the essential multi-temporal nature of geospatial data, as previous acquisitions, historical data, etc. (Rabbia et al, 2020; Brocchini et al., 2017; Gawior et al., 2017) This methodological approach has been applied and proposed in this research in the study framework in the area of Spina Verde Park in Como (Italy) (Figure 1). Spina Verde Park lies in a hilly forested area in the southern part of Como Municipality. Throughout the park's territory, there are numerous sites and archaeological traces belonging to a series of widespread settlements active during the first millennium b.C. (De Marinis et al., 2001).