Digital stone grafting for volumetric reintegration and reconstruction of architectural sculptural-ornamental elements: case study in cultural heritage

The volumetric reintegration of stone architectural elements remains a significant challenge in heritage conservation, particularly when material losses affect the legibility, integrity, or interpretation of sculptural-ornamental features. Traditional approaches, including stone inserts and mortar-based reconstructions, may involve direct intervention on the original material and present limitations related to compatibility, durability, or process control. This study presents and validates a digital stone grafting methodology for the volumetric reintegration of architectural sculptural-ornamental elements. The proposed workflow combines high-resolution three-dimensional recording, digital modelling, and CNC fabrication in stone of identical lithology to the original material. Based on the generation of a digital clone, the methodology enables the documentation, analysis, reconstruction, and fabrication of missing volumes while minimising direct interaction with the heritage asset. The system was applied and evaluated through the full-scale reproduction of a Romanesque capital from the Basilica of Sainte-Marie-Madeleine of Vézelay (France). Validation of the workflow included the assessment of geometric correspondence between the digital model and the fabricated insert, together with considerations of material compatibility and fitting performance at the fracture interface. The results highlight the potential of combining digital technologies and traditional stone-working practices within a hybrid conservation approach, while also discussing the technical, economic, and ethical considerations associated with volumetric reintegration in cultural heritage.