Reality Capture and BIM

Match the capture method to the question

Start with what the data must answer, then choose how it is captured. A tripod-mounted scanner gives dense, careful coverage of a plant room, mobile units carried by hand, on a pole or on a robot cover corridors and floors quickly, a drone reaches roofs and earthworks, and a legged robot can walk the same route on a schedule. Products on our survey page, such as the Emesent Hovermap, GeoSLAM ZEB Horizon, Leica BLK ARC and Spot with HoloBuilder, take different approaches, so ask each maker how its unit is carried and how long a typical floor takes. For progress tracking, consistency between visits matters more than maximum detail, while clash checks before services go in need tighter tolerances.

Verify accuracy with a recognised test

Manufacturers quote accuracy under their own conditions, so ask how each figure was obtained. ASTM E3125-17, reapproved in 2025, gives a test method for evaluating the point-to-point distance measurement performance of medium-range laser scanners, defined as working from 2 to 150 metres. The standard can be used to verify an instrument at acceptance or under warranty and to compare instruments, though it warns that real-world results can differ because of surface properties, object geometry, environment and vibration. Ask whether a maker's tripod scanner has been tested to it. For mobile or drone systems, ask what equivalent check they offer, such as scanning control points of known position on your own site.

Set the exchange rules under ISO 19650-2

Scan data only feeds BIM usefully when everyone knows what is delivered, in which form and at what point. ISO 19650-2:2018 sets requirements for managing information during the delivery phase of assets as a defined process, whatever the project's size or procurement route. Use that process to fix the practical details for scan data: the coordinate system and survey control everyone works to, file formats and naming, and the moment a capture is accepted into the common data environment. Decide too whether each delivery is a raw point cloud, a registered and cleaned cloud, a deviation report against the model or an updated model, because each one takes a different amount of processing.

Turn repeat scans into progress records

The payoff from reality capture comes from comparing visits rather than from any single scan. Fix control points that will survive the build, keep the same route and settings each time, and register every visit to the same coordinate system so that differences reflect construction rather than drift. Compare each capture with the planned sequence to flag missing or late work and anything built outside tolerance, and keep the dated record, since it can settle disputes about when work was done or covered up. Agree who reviews the deviation reports and how quickly, because a report that arrives after the ceiling is closed has lost most of its value. Start with one floor before scaling up.

Sources and further reading

• ISO 19650-2:2018 Information management using building information modelling, Part 2: Delivery phase of the assets — International Organization for Standardization.
  The information management process for the delivery phase of a built asset, usable on projects of any size.
• ASTM E3125-17(2025) Standard Test Method for Evaluating the Point-to-Point Distance Measurement Performance of Spherical Coordinate 3D Imaging Systems in the Medium Range — ASTM International.
  Test method for checking the distance accuracy of laser scanners working from 2 to 150 metres, for acceptance or comparison.

Common questions

What is scan-to-BIM?

Scan-to-BIM is the process of turning a point cloud from laser scanning into a building information model, either by modelling existing conditions from scratch or by updating a design model to match what was built. It takes skilled time, so price it separately from the capture itself.

How often should a construction site be scanned?

There is no fixed rule. Scan at moments when evidence is about to disappear, such as before slabs are poured, walls are boarded or ceilings are closed, and add regular progress captures at whatever interval your programme reviews need.