Digitising the Past with Scan-to-BIM

Heritage and historic buildings pose specific challenges to preservation: irregular geometric shapes, numerous changes over centuries with no documentation thereof, ageing materials, structural instability and delicate architectural elements which all require a high level of attention. Traditionally used documentation methods are sometimes not sufficient to record all aspects of heritage assets. With Scan-to-BIM, 3D laser scanning, photogrammetry and other reality capture tools are employed to create data-intensive BIM models of existing buildings. When used in heritage context, the whole process becomes known as Heritage Building Information Modelling (HBIM). It is a special case of Scan-to-BIM which additionally contains historical, material and conservation-related data besides geometric. Scan-to-BIM is more than just documentation – it is a whole platform for analysis, restoration planning, maintenance and overall heritage management. Numerous studies confirmed its efficiency in creating HBIM models of important heritage assets, such as the Engine House Paços Reais in Lisbon.

By transforming the physical state into a digital model, Scan-to-BIM allows having a better understanding of the building’s conditions and making the responsible decisions accordingly.

 What is Scan-to-BIM for Historic Buildings?

The Scan-to-BIM process for historic buildings is a certain workflow aimed at documenting and interpreting heritage fabric.

Site survey and planning: Teams determine the building’s geometry, access limitations, areas that pose structural or conservation risks, the level of detail required and conservation objectives.

Reality capture: Terrestrial laser scanning, aerial laser scanning (UAV/drone photogrammetry) or both are used to document walls, roofs, façades, decorative elements, structure, defects and other components.

Point cloud processing: Several scans are registered, noise is removed, datasets are aligned and information is organised in a geo-referenced point cloud.

BIM/HBIM modelling: The point cloud is translated into a parametric model containing information about architectural, structural, material and historical aspects of the building. In case of historic buildings, custom object creation is often necessary since standard BIM families do not always accommodate irregular historic elements.

Data integration: Photographs, archival drawings, inspection results, material descriptions, repair history, even current sensor data is linked to the model.

Such model is far more useful than just a 3D visualization as it includes precise geometry along with all information about the building and its life cycle. Scan-to-HBIM workflow usually implies several interrelated steps: data acquisition, processing, parametric modelling and data integration.

 Key Applications in Heritage Preservation

Accurate Heritage Documentation

A dense point cloud allows creating a highly precise (millimetre-accurate) record of the building’s current condition. It serves as a great source of documentation for irregular walls, deformations, ornamentation, areas that cannot be reached and previous alterations which might not be recorded anywhere else. This record can be used in creating conservation reports, archiving documents, insurance valuation and future research. Importantly, this kind of documentation allows establishing a “digital baseline” of the building as it is now prior to any interventions.

 Condition Assessment and Structural Analysis

This process helps the conservation teams to detect cracks, settlements, deformations of the walls and roof and other structural changes which may point at deterioration and/or instability of the building. The survey data can be compared over time for detecting the changes and deformations – it is called deformation analysis. This BIM model is not meant to replace the engineering specialists but it will greatly improve the quality and coordination of the information available by offering a common geo-referenced platform. Engineers can use this model for analysis of relationships between structural elements, load paths and planning of minimal-invasive interventions.

 Restoration and Conservation Planning

It is helpful in planning the restoration of the building by creating an accurate existing-condition baseline. Teams can test different scenarios of intervention virtually and estimate the visual, structural and functional impact of each of them. This function is especially useful in order to minimise the disturbance of original materials during interventions which is one of the main principles of the conservation practice. Information about existing condition is useful in distinguishing original fabric from subsequent alterations.

 Adaptive Reuse of Historic Buildings,

Scan-to-BIM allows creating a digital basis for adaptation of historic buildings to become museums, hotels, offices, cultural centres and other facilities. It helps to integrate various services (architectural, accessibility, fire safety and energy-saving ones) around the protected architectural elements of the building.

 Maintenance and Long-Term Monitoring

This application consists in keeping the BIM model alive and updating it after each inspection, repair or renovation. The BIM model can be used by facility managers to track materials, defects, maintenance schedule and history of the interventions over decades. Long-term monitoring will turn heritage conservation into a planned process of building maintenance. Such application is especially helpful in managing large or complicated heritage estates where different parties are responsible for the maintenance of the building. Scan-to-BIM models allow for planning of the restoration, documentation and maintenance of the heritage estate over its entire life cycle.

 Benefits of Scan-to-BIM for Conservation Teams

  • Higher accuracy: Captures complex geometry and architectural details more precisely than manual measurements and traditional surveying.
  • Improved collaboration: Gives a common digital reference for architects, engineers, conservators, contractors, owners and regulators.
  • Better decision-making: Enables teams to analyse existing condition and possible interventions using one common database.
  • Reduced site disruption: Helps to make plans for the intervention more detailed in advance thus avoiding numerous visits to the site, openings and test interventions.
  • Stronger regulatory documentation: Provides solid grounds for obtaining approvals and conservation evaluations, helps to obtain listed building consents, heritage permits and grant money.
  • Long-term accessibility: Creates reusable database of the building for future repairs, research, emergencies and facility management.

Support for interoperability: HBIM allows combining point clouds, photographs, drawings, GIS data, sensor information and alphanumeric records in one accessible database.

 Challenges and Best Practices

Main Challenges

Non-standard features common in historic structures may require special object creation or simplification due to incompatibility with conventional BIM families. Scan may not cover some of the building’s elements due to occlusions, access limitations, reflectivity or transparency of surfaces, vegetation, or safety concerns related to surveying. High-resolution models may require considerable computing power, memory space, and special modelling skills not available in every conservation team.

Trade-offs in terms of level of detail (geometric accuracy) and level of information (attributed data) need to be made; excessive modeling may result in higher expenses without adding conservation value. Different software platforms and data formats may lead to interoperability issues, especially when dealing with multi-disciplinary projects.

Recommended Practices

  • Identify the goals of the project and required model resolution prior to scanning
  • Supplement laser scanning with photogrammetry when additional colours or textures are required
  • Establish clear naming standards, use metadata, survey controls and quality assurance procedures at all stages of the workflow
  • Indicate uncertainty, rather than present everything in the model as precisely measured – indicate when any interpretation has been done
  • Keep a digital archive under version control with proper documentation of changes and updates
  • Use open formats such as IFC whenever possible to facilitate further collaboration through different software platforms

According to recent research, standardization is considered one of the key issues in making Scan-to-BIM processes consistent and applicable in heritage projects.

 Scan-to-BIM in Historic Preservation: Future

The industry develops fast and now the following technologies are commonly used: automated or semi-automated point-cloud classification, machine learning for feature recognition, UAV photogrammetry for hard to reach areas, digital twin platforms for real-time monitoring, sensor network for environmental monitoring. Automation can speed up the process of modelling of repetitive or recognisable parts, such as columns, windows, regular masonry, etc. While automated methods can significantly facilitate the process, human expertise will still be necessary for modeling of unique elements of historic architecture, irregular construction and cultural features. Possible integration with GIS, virtual reality, augmented reality, and condition-monitoring system suggest even more sophisticated platforms for heritage management in the future.

Whatever new technologies will come along, the main principle of using technologies in heritage will always stay the same: technology should be used in service of conservation values: authenticity, minimal intervention, reversibility where possible, and respect for cultural significance.

 Conclusion: Digital Basis for Responsible Preservation

Scan-to-BIM combines accurate surveys and heritage management in an effective way that is changing the approaches to conservation of historic buildings. Its applications in documentation, condition assessment, restoration planning, adaptive re-use, compliance with regulations and maintenance make it an indispensable tool for responsible conservation. The most valuable result of this process is not just aesthetically pleasing model, but information environment that can support decision-making throughout the life cycle of the building. Thus, the message to heritage owners and project teams is very clear: establish clear information needs, involve experienced conservators, choose a Scan-to-BIM workflow suitable for your heritage building.

Precisely Protect Your Heritage – Choose Camellia Buildtech

Camellia Buildtech has built its success on providing precise and data-filled Scan to BIM and HBIM solutions for heritage properties. Our experts are proficient in using the latest reality capture technology such as terrestrial laser scanning, UAV photogrammetry, and point cloud processing.

FAQs

1. What is Scan-to-BIM in heritage conservation?

Scan-to-BIM is the process of translating 3D laser scan, photogrammetry and point cloud data into a BIM or Heritage BIM model. The latter is a model of historic building that contains geometry, materials, defects, architectural details, historical information and maintenance history in one easily accessible digital environment.

2. How does Scan-to-BIM help preserving historic buildings?

It makes possible to create a digital record of the current state of the historic building, helps with conducting condition assessments, developing plans for restoration work, minimizes design errors and provides long-term archive. The model can also help in carrying out future inspections, maintenance works and emergency planning.

3. What is the difference between Scan-to-BIM and HBIM?

Scan-to-BIM is the workflow of creating a BIM model based on survey data. HBIM or Heritage Building Information Modeling is a BIM technique focused on heritage buildings. It incorporates historical, architectural, materials, conservation and cultural information in addition to geometric data.

4. Can Scan-to-BIM be used for damaged or irregular historic buildings?

Yes, Scan-to-BIM is especially suitable for buildings with irregular walls, deformations, decorative elements, modifications that are not recorded and irregular constructions. However, the process of modelling may require special expertise as standard BIM objects may not provide accurate representation of unique heritage elements.

5. Which technologies are used in heritage Scan-to-BIM project?

Among common technologies used for the purpose are terrestrial laser scanners, UAV photogrammetry, close range photogrammetry, point cloud processing software, BIM authoring software, GIS, digital camera, and monitoring sensors. The correct combination of them will depend on the size of the building, its accessibility, required accuracy and conservation purposes.

6. How much does Scan-to-BIM for a historic building cost?

The cost depends on the size of the building, its complexity, accessibility, chosen survey technique, required accuracy, level of detail, scope of the model and amount of historical or maintenance information to be added. Clearly stated survey brief and BIM requirements will help in avoiding unnecessary scanning and modeling costs.