What Scan-to-BIM actually involves
Scan-to-BIM is the process of turning 3D scan data – from terrestrial laser scanning, drone photogrammetry, or drone LiDAR – into a Building Information Model in Revit, ArchiCAD, or Bentley. The BIM model is a geometrically accurate, intelligent 3D representation of what’s actually there, useful for design, analysis, and facilities management.
Drone data has become a big part of Scan-to-BIM workflows, particularly for building exteriors, roofs, site context, and large infrastructure that you can’t practically survey from ground level.
What the drone contributes
Roofs and upper facades
Terrestrial scanners are great for interiors but they can’t see roofs, upper facades, or anything without clear line-of-sight from ground level. Drones fill that gap:
- Complete roof geometry – ridges, valleys, hips, eaves, parapets, roof plant, access structures
- Upper facade detail – windows, cladding joints, structural elements, defects on upper storeys
- Full building envelope that combines with interior scan data for a complete model
Site context
BIM models need accurate surroundings for coordination, planning compliance, and presentations. A drone topographical survey gives you:
- Existing ground levels and terrain
- Adjacent buildings, roads, infrastructure
- Vegetation, boundaries, site features
- Utility corridors and access
Large infrastructure
For infrastructure BIM – bridges, retaining structures, embankments, road corridors – drones capture external geometry far more efficiently than terrestrial scanning. A bridge that would need multiple scanner setups and possible lane closures can be captured in one flight.
The workflow
Stage 1: Data capture
We plan specifically for Scan-to-BIM:
- Grid plus oblique (45 degree) flight pattern to cover all facades and roof surfaces
- Low altitude, high overlap for sub-centimetre resolution on architectural detail
- GCPs surveyed in the project coordinate system so drone data aligns with terrestrial scan data
Stage 2: Point cloud generation
Photogrammetric processing produces a dense, coloured point cloud. For LiDAR, the cloud comes directly from the scanner data. Either way, accuracy gets verified against check points – typically plus or minus 2 to 5 cm.
Stage 3: Registration and merging
If the project has both terrestrial scanning (interiors) and drone survey (exteriors/roof), the datasets need to be registered – aligned into one coordinate system. We do this through:
- Shared survey control points visible in both datasets
- Cloud-to-cloud registration using overlapping areas (usually facades captured by both)
- Quality checking the merged result
Stage 4: BIM modelling
The registered point cloud goes into Revit (or whichever platform) as a reference. Modellers trace geometry from the cloud to create BIM objects – walls, floors, roofs, columns, windows, MEP. Detail depends on the LOD specified:
- LOD 200: Approximate geometry – feasibility and concept
- LOD 300: Accurate geometry with correct dimensions – detailed design coordination
- LOD 350: Accurate geometry with connections – construction coordination
Accuracy
Drone data
- Photogrammetry point cloud: plus or minus 2 to 5 cm absolute (with GCPs)
- LiDAR point cloud: plus or minus 2 to 3 cm
- Surface detail: features 5 cm and larger are typically resolvable
BIM model
- LOD 200: plus or minus 5 to 10 cm – representative but approximate
- LOD 300: plus or minus 2 to 5 cm – accurate as-built dimensions
- LOD 350: plus or minus 1 to 3 cm – supports clash detection
For most renovation and extension projects, LOD 300 from drone data is appropriate and achievable. More in our accuracy guide.
Where drone data is essential
- Heritage and conservation: complex roofs, inaccessible upper elements, facade detail on protected structures
- Large commercial buildings: roof plant, multiple roof levels, extensive site context
- Infrastructure: bridges, retaining walls, structures with limited ground access
- Campus sites: where relationships between buildings matter as much as individual geometry
What we deliver
Cleaned, classified point clouds in formats for Revit (via ReCap), ArchiCAD, and Bentley. For combined terrestrial plus aerial projects, we coordinate with your scanning team to ensure everything merges cleanly.
Get in touch about your Scan-to-BIM requirements, or see our 3D modelling service.