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Scan to BIM describes the process of capturing an existing building using digital surveying technologies and then converting it into a Building Information Model (BIM). First, geometric data is recorded using 3D laser scanning, LiDAR or photogrammetry. The captured data, usually in the form of point clouds, is then used to create a structured BIM model containing geometries, building elements and further building information.
Scan to BIM provides the basis for digitally representing existing buildings and integrating them into modern BIM processes as BIM for existing buildings.
Why is scan to BIM important?
- Reliable data basis: The current as-built condition reduces planning errors, change orders and site visits.
- Efficient workflows: Direct transition from capture to models, drawings and quantities, without media breaks.
- Collaboration: Open formats, such as IFC, support data exchange and help prevent vendor lock-in.
- Verification and compliance: Documented tolerances, checkpoints and change logs increase trust, legal certainty and funding opportunities.
How scan to BIM works in practice
- Capture: Digital measurement using terrestrial laser scanning (TLS), mobile LiDAR/SLAM or photogrammetry creates point clouds and image data for the existing condition survey.
- Registration/QA: Scans are aligned using target-based or cloud-to-cloud registration; checkpoints, RMS errors and tolerance classes are documented; coordinate system and units are defined.
- Modelling: Semantic building elements such as walls, slabs, openings, stairs and MEP objects are derived in the appropriate LOD/LOI; naming and parameter standards are applied.
- Review: Clash checks, attribute completeness checks, model and coordinate reviews, and visual comparisons with the point cloud are carried out.
- Handover/use: Delivery as IFC for the BIM model, 2D drawings in DWG/DXF/PDF and room books or lists; integration into coordination, tendering, CAFM or digital twin workflows.
Level of detail and use cases
- LOD/LOI according to purpose: Envelope model for variants and quick studies; detailed building elements and parameters for execution, MEP and billing.
- Deformation-accurate model: Representation of real deviations, such as uneven walls or settlement, in existing buildings.
- Discipline models: Architecture, MEP and structural models are created separately and used in a coordinated way.
Common mistakes and misunderstandings
- “Many points automatically mean a good model”: Without QA, checkpoints, RMS values and clean registration, systematic deviations can occur.
- Over- or under-modelling: An LOD/LOI that is too high or too low makes projects more expensive or limits later use. The model should be aligned with the objective.
- Unclear coordinates/units: Missing information on m/mm, origin or coordinate system makes exchange and operation more difficult.
- Only geometry, no attributes: Missing property sets prevent quantities, verification and CAFM integration.
- No versioning: Changes without a change log lead to inconsistencies between planning and operation.
FAQ
What level of detail makes sense?
It should be aligned with the use case: an envelope model for variants and quantity frameworks; higher LOD/LOI for execution, MEP coordination and billing. This should be documented in the model guidelines.
How do I ensure quality and traceability?
Through checkpoints with RMS values, documented tolerances and classes, viewer and attribute checks, visual comparisons with the point cloud and a change log.
Which formats are delivered?
IFC for the BIM model, DWG/DXF/PDF for 2D derivatives and E57/LAS/LAZ for point clouds, each with metadata on version, units, coordinate system and accuracy.