Scan to BIM: how it works and what affects the cost

The idea

Old drawings of existing buildings are often out of date or simply wrong. Scan to BIM replaces guesswork with measurement. A laser scanner records the building as millions of points in 3D, called a point cloud. A modeler then builds a BIM model over that cloud, so the walls, floors, beams and pipes in the model are where they really are.

The five steps

1. Scan: a survey team captures the building with a laser scanner.
2. Register: the separate scans are stitched into one point cloud in a shared coordinate system.
3. Model: the modeler builds architecture, structure and visible services over the cloud in Revit.
4. Check: the model is compared with the cloud to show where they agree and where they do not.
5. Deliver: the model, a deviation report, and a record of what could not be seen.

File formats

We work from the common point cloud formats: RCP and RCS (Autodesk ReCap), PTS and E57. Ask your survey partner to export to the one that suits your workflow and to include control points.

Level of development and level of accuracy

Two settings define the job. Level of Development, LOD, says how detailed each element is. Level of Accuracy, LOA, from the US Institute of Building Documentation, states how closely the model must match the scan. A heritage survey may need a tight tolerance and rich detail; a space-planning model for an office fit-out may not. State both in the brief.

What a scan cannot see

A scanner records only what is visible. Services above ceilings, inside walls or under floors are invisible to it. Good practice is to mark these in the model as assumed or unknown, never to draw them as if they were verified.

What decides the cost

1. Area: larger buildings take longer to model.
2. Level of development and accuracy: more detail means more hours.
3. Services density: modeling dense MEP from a cloud is slow work.
4. Complexity: curved geometry, heritage detail and irregular structure cost more than regular boxes.
5. Point cloud quality: noisy, patchy or poorly registered data takes more time to interpret.
6. Deliverables and deadline: sheets, schedules, deviation reports and short deadlines all add to the effort.

How it is priced

Scan to BIM is usually quoted per square foot or square meter for straightforward architectural scope, per hour or day for complex or uncertain work, or as a fixed price for a defined scope. Published vendor guides show a very wide spread, from well under a US dollar to a few dollars per square foot depending on detail and services density, which is why a reliable quote needs a look at your point cloud and your required level of detail.