What Is SLAM Scanning?
SLAM (Simultaneous Localisation and Mapping) scanning is a mobile LiDAR technology that lets a surveyor walk through an environment — carrying a handheld or backpack scanner — while the device simultaneously builds a 3D point cloud map and tracks its own position within it, all without GPS.
SLAM scanners combine LiDAR sensors, cameras, and inertial measurement units (IMUs). The SLAM algorithm continuously cross-references new scan data against previously captured geometry — "loop closures" — to correct for positional drift and build a coherent dataset in real time.
Key Benefits
| Benefit | Detail | | --- | --- | | Speed | A site taking 11 hours with a total station can be captured in ~2 hours — 5–10× faster than tripod methods | | No GPS required | Works underground, inside buildings, in urban canyons, and tunnels | | Comprehensive coverage | Live visual feedback lets operators fill data shadows on the fly | | Safety | Operators can scan from safe distances — removing the need to enter traffic or work at heights | | BIM-ready output | Point clouds export directly into Revit, AutoCAD, and GIS platforms | | Revisit surveys from the office | A captured dataset allows virtual re-measurement without returning to site |
When to Use SLAM Scanning
| Ideal For | Less Ideal For | | --- | --- | | Large or complex interior areas (warehouses, hospitals, multi-floor offices) | Very small spaces (<100 m²) where set-up cost isn't justified | | GPS-denied environments (underground, tunnels, basements) | Sub-5mm tolerances (e.g., structural steel QA/QC) | | Construction progress monitoring against BIM | Legal/boundary disputes requiring tripod precision | | Measured building surveys for refurbishment | Repetitive featureless geometry where SLAM can drift | | Rapid as-built documentation on live sites | Heritage preservation requiring maximum geometric precision |
Accuracy
Modern top-grade SLAM systems (NavVis VLX 3, GeoSLAM Horizon) achieve 5mm or better accuracy when the point cloud is snapped down to survey control points established by total station or GNSS. Without georeferencing, general SLAM accuracy is approximately 1–3% of total distance travelled due to drift accumulation.
Costs (UK 2025)
| Service | Typical Cost (ex VAT) | | --- | --- | | On-site day rate | £1,000–£1,500/day | | Point cloud + CAD drawings | £1,000–£2,000/drawing set | | Full BIM/Revit model | £1,500–£5,000+ | | Scanner hire (self-operated) | Available through SEP Geospatial and 3D Hire Hub |
Frequently Asked Questions
Q: How accurate is SLAM scanning?
Top-grade SLAM systems achieve 5mm or better when georeferenced to survey control points. Without georeferencing, accuracy is approximately 1–3% of distance travelled. For construction documentation, georeferenced SLAM is typically sufficient.
Q: When should I choose SLAM over tripod scanning?
Choose SLAM for large interiors, GPS-denied environments (tunnels, basements), construction progress monitoring, and fast turnaround. Choose tripod scanning for sub-5mm tolerances, boundary disputes, or very small projects.
Q: Does SLAM work underground or indoors without GPS?
Yes — SLAM does not require GPS and works entirely independently of satellite positioning. It is ideal for tunnels, basements, mines, and urban canyons.
Q: What deliverables can I get from SLAM scanning?
Registered point clouds (.e57, .rcp, .las), georeferenced surveys, 2D CAD drawings, 3D Revit/BIM models, and digital twins for asset management.