Rapid 3D Survey and GIS-Based Workflow for Heritage Risk Assessment. The Case Study of Mirandola, Italy

Abstract. This paper investigates rapid survey methodologies for urban environments to support the compilation of the Italian Carta del Rischio del Patrimonio Culturale (Risk Map of Cultural Heritage, GIS developed by the Italian Ministry of Culture), with a focus on the documentation and assessment of Building Fronts in historic centres. The study addresses the need for acquisition strategies that balance accuracy requirements with constraints related to survey time and costs, while ensuring flexibility and long-term updatability. The proposed workflow was tested on a complete urban block in the historic centre of Mirandola (Modena, Italy), characterised by dense urban morphology, narrow streets, and ongoing post-seismic reconstruction. Data acquisition was based on spherical photogrammetry as the primary rapid survey technique, complemented by Google Street View panoramas to support diachronic analysis of façade transformations. A high-accuracy reference survey integrating Terrestrial Laser Scanning and Close- Range Photogrammetry was carried out on a limited portion of the block to validate the rapid survey results. Different ground control configurations were evaluated to assess the trade-off between acquisition speed and metric accuracy. All survey products and diachronic imagery were integrated into a GIS-based information system structured according to the Carta del Rischio data model. The system enables immersive visualization of panoramic images, metric inspection of façade orthophotos, and structured data management, supporting monitoring, risk assessment, and conservation activities in historic urban contexts.