To achieve the goal of complete digitalisation of the Romanesque-style rural church of São João de Calvos (Guimarães, Northern Portugal), the team led by Fabio Sitzia (HERCULES – University of Évora / IN2PAST) took advantage of the November fieldwork campaign to also three-dimensionally reproduce the building, in order to be able to analyse the Heritage – Building Information Modelling (H-BIM) protocols.

H-BIM is a digital method for the conservation and management of architectural heritage. Using technologies such as 3D laser scanning, photogrammetry and drones, it creates detailed digital models to analyse conservation status, plan restorations, and monitor structures over time.

The digital survey of the Romanesque-style church in Guimarães integrated 3D recording methodologies based on photogrammetry (precise measurements by photographic methods), enabling the high-resolution capture of the chapel’s architectural and decorative details. The combination of aerial images obtained using UAS (Unmanned Aerial Systems) and terrestrial data ensured an accurate representation of the building’s dimensions and characteristics, while advanced digital processing techniques generated three-dimensional models faithful to the structure’s current state.

The digital model is online available here.

The team used a DJI Mavic 2 drone equipped with a high-precision camera (1″ CMOS sensor with 20 million pixels) for both the aerial survey of the exterior and the image capture of the chapel’s interior. A micro-photogrammetry survey was also conducted, since the final H-BIM model will contain a range of geometric information, useful for monitoring the building.

A Nikon D3300 camera was used to produce reliefs of specific parts of the monument, classified as a Property of Public Interest in 1955, considered as sensitive areas. Among these are areas subject to rain runoff, water rebound or capillary rise and, in general, wall portions affected by fractures. Thanks to the high level of detail offered by this photogrammetry, it is possible to evaluate the surface recession of the stone by repeating the survey for pre-established periods, for example two years.

In addition to these digitisation works, the team also started mapping the types of materials, its mechanical properties and decay, information which will be displayed in the final 3D model through coloured thematic layers (pasted directly with a transparency of 70% so that the underlying raster image can also be viewed).

Another important characterisation performed on the walls was the measurement of the  materials’ compressional wave velocities, using an ultrasonic pulse velocity instrument. Compressional wave velocity (Vp) is the speed at which a wave propagates in a series of compressional motions through the material. Higher wave velocities indicate better material quality, assuming the same lithology.