3D Low-Cost Multispectral UAV Systems: survey and analysis of ‘Torresino da Polvere’ of San Marco in Bergamo

The Torresini da Polvere are special constructions built by the Venetian Republic between the 16th and 18th centuries. They are unique architectural structures, characterized by a pyramidal roof, for the preservation of the gunpowder. The torresino of San Marco in Bergamo is one of the best-preserved in the world and was then the subject of detailed research. The powder magazine was measured by professional, ground-based and airborne instruments. The paper shows a comparison between the existing structure and the photogrammetric model obtained by low-cost UAV systems to formulate an accurate estimate, including the pros and cons of different survey systems. It also aims to deepen the aspects associated with 3D reconstruction using multispectral imagery, from the investigation to data processing, to create models with NDVI mapping for the study of the building’s decay caused by biological agents.