By Nidhi DhullReviewed by Susha Cheriyedath, M.Sc.Nov 20 2024A recent article published in Heritage developed a workflow that uses a scan-to-Building Information Modeling (BIM) approach to create a decay map as part of Heritage Building Information Modeling (HBIM). This method 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 Building Information Modeling (BIM) has significantly advanced architectural heritage management by enabling the creation of three-dimensional (3D) parametric models that detail essential information for restoration and conservation procedures. When applied to architectural heritage for preservation purposes, this process is referred to as Historical or Heritage BIM (HBIM).
However, HBIM faces several limitations. A key issue is that the BIM framework lacks dedicated families of objects tailored to decay mapping and other specific aspects of architectural conservation. As a result, degradation mapping is often limited to two-dimensional graphical visualization, without an integrated database to store and manage all decay-related information.
To address these challenges, new applications are needed to standardize approaches within the HBIM field. This study proposes a decay mapping method that operates within the 3D BIM model, utilizing custom families and a specialized abacus developed directly in the BIM environment.
Methods
A scan-to-BIM-based approach was utilized for the digitization and thematic mapping of decay phenomena in the ancient church of “Santa Maria della Grotta.” Given the unique sandstone composition of the church and its placement, monitoring methods were essential to preserve its architectural integrity. To achieve optimal results during the acquisition phase, critical issues and preferred approaches were identified in advance.
A detailed 3D survey was conducted using laser scanning technology and photogrammetry to capture the site’s as-is conditions. A handheld mobile laser scanner (HMLS) was employed as a cost-effective and efficient tool for the rapid and dynamic acquisition of the entire complex. Additionally, a drone was used to capture the exterior of the church.
The acquired geospatial data was processed to create a comprehensive 3D model of the entire church. Photogrammetric processing was carried out using Agisoft Metashape software, which employed the Structure from Motion (SfM) algorithm. Ground control points were integrated to solve the bundle adjustment during the optimization phase.
Decay analysis was performed based on the texture information extracted from orthophotos of the church’s internal and external main walls. The survey data was then used to develop a BIM model using Autodesk Revit software. Decay maps were generated on the main surfaces of the HBIM model by analyzing building degradations. These decays were categorized according to the International Council on Monuments and Sites (ICOMOS) glossary, with distinctive colors and patterns assigned to each type of degradation for immediate visual recognition and classification of 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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