3D solid model updating of complex ancient monumental structures based on local geometrical meshes

Finite element analysis (FEA) is used to analyze the static and dynamic structural behavior providing important information for the conservation of monuments in cultural heritage. Accurate solid models are fundamental in this type of analysis, but the structural changes introduced during the lifetime of the monument produce complex geometrical configurations that may not be generated with the desired accuracy in standard CAD solid modeling software. On the other hand, techniques such as laser scanning or photogrammetry can reproduce accurate geometrical information but only of the surface of the monument which cannot be directly applied for FEA. We introduce a novel methodology for locally updating an existing 3D solid model of a complex monumental structure with the geometric information provided by a 3D mesh extracted from the digital survey of a specific sector of the monument. The methodology starts by registering the new information from the digital survey to the existing solid model of the monument. The difference between the models is used to highlight the region of interest (ROI) to be updated. The ROI is encapsulated and transformed into a solid space where Boolean operations are used to update the original solid model. We test the procedure on Huaca de la Luna, Trujillo, Peru, one of the most important massive earthen structures of the Moche civilization. Solid models are defined in AutoCAD while 3D meshes are recorded with a Faro Focus laser scanner. The results indicate that the proposed methodology is effective at transferring complex geometrical and topological features from the mesh to the solid modeling space.