By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.Nov 20 2024A recent article published in Heritage described a workflow based on a scan-to-building information modeling (BIM) approach to generate a decay map within Heritage Building Information Modelling (HBIM). The workflow was applied to the “Santa Maria della Grotta” church in Marsala (Italy).
Study: Scan-to-BIM Process and Architectural Conservation: Towards an Effective Tool for the Thematic Mapping of Decay and Alteration Phenomena. Image Credit: SWKStock/Shutterstock.com
Background
Adopting BIM has significantly benefitted architectural heritage management through three-dimensional (3D) parametric models detailing essential information for restoration and conservation procedures. A BIM-based digitalization applied to architectural heritage for preservation purposes is termed Historical or Heritage BIM (HBIM),
However, HBIM has several limitations. Primarily, the BIM framework does not host proper families of objects dedicated to decay mapping or other specific aspects of architectural conservation. This often reduces the degradation mapping process management to a two-dimensional graphical visualization only, without a database where all the decay information can be reported and stored.
Therefore, new applications are required to standardize approaches in the field of HBIM. Accordingly, this study proposed a decay mapping method that works over the 3D BIM model using ad hoc families and a specific abacus created inside the BIM environment.
Methods
A scan-to-BIM-based approach was employed for digitization and thematic mapping of the decay phenomena of the ancient church of “Santa Maria della Grotta.” Apart from the unique sandstone complex of the church, its placement required monitoring methods to preserve the state of the architecture. Therefore, critical issues and a preferable approach were identified before the survey to obtain the best result in the acquisition phase.
A detailed 3D survey using laser scanning technology and photogrammetry was planned to acquire the site’s as-is conditions. A handheld mobile laser scanner (HMLS) was used as an efficient and cost-effective solution for the fast and dynamic acquisition of the whole complex. Additionally, the exterior of the church was captured using a drone.
The acquired geospatial dataset was processed to obtain a complete 3D model of the whole church. The photogrammetric processing was performed through Agisoft Metashape software. Specifically, the software’s Structure from Motion (SfM) algorithm integrated various ground control points to solve the bundle adjustment procedure of the optimization step.
The decay analysis was performed based on the texture information provided by the orthophotos of the church’s internal and external main walls. Subsequently, the survey data was used to prepare a BIM model using Autodesk Revit software. Finally, decay maps were generated over the main surfaces of the HBIM model based on an analysis of the degradations of the building. Subsequently, the decays were mapped according to the International Council on Monuments and Sites (ICOMOS) glossary, assigning a distinctive color and pattern to each degradation for immediate visual recognition and classification of different anomalies.
Results and Discussion
The HBIM methodology used for the thematic degradation mapping of a church optimized the survey acquisitions. The thematic mapping utilized the quality of orthophotos acquired by the photogrammetric survey to enable a 3D analysis of the decays.
The parametric objects signifying the decay in the HBIM model allowed for calculating areas of interest, helping the church’s maintenance team predict the costs of probable restoration interventions. Additionally, the 3D representation of decays in the external and internal walls of the main nave in the BIM environment enabled correspondence between external and internal states of degradation, enhancing awareness of the church’s state.
The digital model encompassed all the acquired documentation and could be repeatedly expanded, retrieved, and updated over time without losing track of previous configurations. This approach could assist in periodic monitoring, with a regular update on the church’s degradation state in the HBIM model.
The HBIM method enabled monitoring, updating, and controlling the potential advancement of pathogen phenomena. Moreover, the evolution of external façade decays over time, including their expansion and seriousness, could be constantly monitored. The identified decays and their semantic peculiarities, such as causes, affected material, intervention cost, etc., eased conservation and restoration plan activities.
Conclusion
Overall, the researchers successfully demonstrated a scan-to-BIM approach as an efficient tool for conservation, preservation, and restoration activities due to its feasible architectural heritage information management system, which is shareable across different collaborative platforms. Moreover, the semantic data about the structure’s degradation state was implemented in the proposed HBIM framework.
An integrated, multi-source survey using mobile laser scanning and terrestrial and aerial photogrammetry effectively supported the development of an accurate 3D model of monumental architectures with complex and articulated parts. Moreover, the ICOMOS glossary, used as the reference to construct the abacus of decays, helped implement a standardized approach to create the database of loadable families.
The proposed common standard reference expanded the dataset for the present case study (reporting extensions, descriptions, causes, and locations on ad hoc sheets and integrating restoration methods, costs, or other specificities related to the building management). Additionally, it can be replicated by specialists in future case studies.
Journal Reference
Aricò, M., Ferro, C., Guardia, M. L., Brutto, M. L., Taranto, G., & Ventimiglia, G. M. (2024). Scan-to-BIM Process and Architectural Conservation: Towards an Effective Tool for the Thematic Mapping of Decay and Alteration Phenomena. Heritage, 7(11), 6257–6281. DOI: 10.3390/heritage7110294, https://www.mdpi.com/2571-9408/7/11/294
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