An Open Tool for the Geometric Proofing and Uncertainty Assessment of 3D Hypothetical Architectural Reconstructions

This paper presents a series of open-source tools developed within the CoVHer Erasmus+ project, designed for geometric proofing and uncertainty assessment of 3D hypothetical architectural reconstructions. Addressing a critical gap in digital cultural heritage workflows, the tools facilitate rigorous verification and uncertainty assessment of complex 3D models, aligning with FAIR principles, the London Charter, and the Seville Principles. The Blender-Uncertainty-Calculator plugin enables both expert and inexperienced users to conduct batch geometric checks and aid the uncertainty assessment through an intuitive interface. Custom properties, including uncertainty and relevance factors, are embedded within the 3D scene data, ensuring long-term accessibility and machine readability. The plugin incorporates a 7-level uncertainty scale tailored for never-built or lost architecture, supporting clear visualization and mathematically consistent global metrics (AU_V and AU_VR) for averaging uncertainty weighted by volume and element relevance. The complementary tool developed for NURBS-based modeling in Rhinoceros via Grasshopper addresses the distinct requirements of mathematical surface geometries. Benchmarking on a complex Palladian model demonstrates substantial efficiency improvements over manual checks. This open framework promotes transparency, reproducibility, and broader reuse of reconstructive models in research, education, and heritage dissemination. Ongoing development addresses usability enhancements and extended documentation capabilities. By democratizing advanced verification and uncertainty assessment tools through popular open-source software, the CoVHer project advances methodological rigor and supports the sustainable and objective digital preservation of architectural heritage.