The urban void of the Mellah in Sefrou’s Medina, reflections through integrated digital methodologies

Abstract. The paper illustrates the outcomes of documentation activities carried out on the Mellah of Sefrou, an area historically subject to recurrent flooding, including a particularly significant event recorded in 1950 that caused severe damage to the built structures and led to an “urban void.” In May 2017, within a workshop organised by the University of Florence in Sefrou, a digital survey campaign was conducted in the area affected by the floods, integrating direct measurements with Structure-from-Motion (SfM) photogrammetry. The aim was to produce three-dimensional datasets supporting the development of 3D models and two-dimensional drawings useful for describing the state of conservation of the structures. In parallel, an alternative workflow was tested, based exclusively on open-source data available online, and in this first phase, focused on modelling the topographic surface of the area. The investigation seeks to explore the potential of open-source geospatial data for generating three-dimensional models, assessing their reliability through comparison with field survey results, defining the effective scale of detail that can be achieved, and identifying possible application domains for products derived from such resources.