BIM IQ

What Is Scan to BIM? The Process, LOD and Accuracy Specs, Deliverables and How to Scope It

By Kush Agarwal, President and CEO, YelloSKYE. Published 2026-10-19.

Executive Summary

• The Question: What is Scan to BIM, how does a scan become a usable model, and what should you specify when you commission one?
• The Answer: Scan to BIM captures existing conditions as a point cloud and then models them, element by element, into a BIM file. A good scope fixes the purpose, the area, the elements, the level of development, the level of accuracy and the formats before anyone starts scanning.
• The YelloSKYE Angle: BIM IQ models existing conditions from laser scanner and drone data at LOD 200 to LOD 400, registered to the project's coordinates and checked against design where needed.

Scan to BIM is the process of measuring a building or structure as it exists, usually with a laser scanner, and modelling what was measured into a Building Information Model. The scan supplies the geometry; the modelling turns that geometry into walls, slabs, columns, openings and services that design and engineering software can work with. The result is a model of reality, not of intent.

YelloSKYE delivers this through BIM IQ, which builds as-built models from the point clouds that laser scanners and survey drones produce. This guide explains what Scan to BIM produces, the steps from scan to model, how level of development and level of accuracy are specified, what you should expect to receive and how to write a scope that gets you the model you need. If you want to understand the scanners themselves, read our guide to laser scanning in construction first.

What Scan to BIM produces, and what it does not

People often use "the scan" and "the model" as if they were the same. They are different products, built for different jobs.

The point cloud on its own is valuable, and it should always be handed over with the model. But it cannot tell you which surfaces belong to a fire-rated wall, how many doors are on a floor or which duct serves which zone. That interpretation is what the modelling step adds, and it is where most of the time and cost sit.

Scan to BIM also only models what the scanner could see. Services above a closed ceiling, reinforcement inside concrete and pipes buried in walls are not in the cloud. A scope that expects them needs opening-up works, existing drawings or a clear note that they are assumed.

From scan to model, step by step

1. Agree the purpose

Everything downstream depends on what the model is for. A space-planning model for a tenant fit-out and a model for prefabricated services in a plant room need different detail, accuracy and coverage. Write the purpose down in one sentence before anything else.

2. Set up survey control

Control points tie the scans to a coordinate system shared with the rest of the project. On a standalone renovation that may be a local grid; on a building joining a wider site it should match the site survey. How this alignment is kept through the project is covered in our guide to reality capture and BIM.

3. Capture

Terrestrial scanners record interiors, structure and plant from a series of set-ups. Drone photogrammetry or LiDAR covers roofs, facades and the surrounding site. BIM IQ takes input from Leica, FARO, Trimble and Matterport scanners and from drone photogrammetry, in .pts, .xyz, .e57, .las, .rcp and .pcg files.

4. Register and clean the cloud

Individual scans are joined into one cloud and placed on the control. Noise, people, furniture that will be removed and reflections from glass are cleaned out, and the cloud is often split by floor or zone so modellers can work in manageable pieces.

5. Model the elements

Modellers trace elements from the cloud in BIM software, choosing the right object type for each and fitting it to the measured surfaces. Some extraction can be automated, such as detecting planes for walls and slabs or cylinders for pipes, but judgement is still needed where the building is irregular: walls that are not plumb, floors that are not flat and openings that do not line up floor to floor.

6. Check the model against the cloud

Before delivery, the model is compared with the point cloud to see how far each modelled surface sits from the measured one. This deviation check is the evidence that the model meets the accuracy agreed in the scope, and it should come with the deliverable.

7. Deliver and hand over

The model, the registered point cloud and the supporting reports are issued in the agreed formats and software versions. BIM IQ imports and exports Revit, Navisworks and ArchiCAD files, supports open BIM exchange through IFC and has integrations for Procore, BIM 360 and ACC.

LOD and LOA: the two specifications that matter

Most Scan to BIM disappointments come from a scope that says "LOD 300" and nothing else. Two separate scales are needed.

Level of development (LOD)

Level of development describes how fully an element is modelled and how reliable its information is. The commonly used definitions come from the BIMForum Level of Development Specification.

A single model rarely needs one LOD throughout. Structure and the building envelope may be at 300, the main services at 350 and furniture left out altogether. YelloSKYE delivers Scan to BIM from LOD 200 to LOD 400 depending on the capture method and the project, and the bulk of its renovation and as-built checking projects are delivered at LOD 300 to 350. LOD 500 is sometimes used loosely to mean "as-built", but in most frameworks it describes field verification rather than more geometry, so state what you mean.

Level of accuracy (LOA)

LOD says nothing about whether an element is in the right place. Level of accuracy does. The US Institute of Building Documentation (USIBD) publishes a widely referenced Level of Accuracy Specification that groups tolerances into bands, stated at a 95 per cent confidence level.

The specification also separates the accuracy of the measurement (the point cloud) from the accuracy of what is represented (the model). That distinction matters: a precise scan can still produce a model that has been simplified, for example by straightening a wall that bows.

Putting the two together

A useful scope sets LOD and LOA per element group. Structural columns and slab edges that new steel will connect to might need LOD 350 with a tight LOA; partition walls being demolished might need LOD 200 with a loose one. Asking for the tightest values everywhere makes the model slower and more expensive without helping anyone, while asking for loose values everywhere leaves the critical interfaces unproven.

What you should receive

YelloSKYE exports Scan to BIM outputs in formats including DWG, DXF, RCP, LAS, OBJ and FBX, alongside native model files, so the data drops into the software design and engineering teams already use.

Where Scan to BIM is used

Renovation, retrofit and adaptive reuse

This is the classic case. Existing drawings are missing, out of date or never reflected what was built, and every consultant needs the same reliable base before design starts. The renovation use case shows how BIM IQ turns an existing building into a design-ready model of its walls, slabs, columns, openings and visible service zones before scope is fixed, and lists the assets that gain most, from offices and warehouses to hotels and hospitals.

As-built verification during construction

On new work, scanning after a critical milestone, such as a slab pour or a steel frame, and comparing the result with the design model shows deviations while they are still cheap to correct. The clash detection use case on our site shows how laser scans are overlaid on the design in Navisworks or Revit so a misplaced core or a missing sleeve is caught before the next trades arrive. For running a whole build against the model, see our guide to BIM in construction.

Facilities management and handover

Operators need a model that matches the building they are taking over, not the one that was designed. A scan-based as-built model gives facility managers a reliable starting point for maintenance, future fit-outs and space changes, and it can sit alongside the visual construction record described in our handover documentation use case.

Plant rooms and services upgrades

Replacing chillers, adding risers or rerouting services through a congested ceiling void depends on knowing exactly where the existing pipes, ducts and structure are. Scan to BIM at a higher LOD for the affected zone, and a lower one elsewhere, gives designers the clearances they need without modelling the whole building in fine detail.

How to scope a Scan to BIM project

A short, specific scope prevents most disputes about what was "meant" to be in the model. Work through these items with the provider before capture.

Two further questions help. Who will use the model next, and in what software? And will it be kept up to date after delivery, or used once and archived? The answers change how much information each element should carry.

Where Scan to BIM projects go wrong

• No stated purpose. The provider guesses, and the model is either too thin to design from or far too heavy to open.
• LOD without LOA. The model looks complete but nobody agreed how close it had to be to reality.
• Assumed hidden services. The client expects pipes behind ceilings that the scanner could never see.
• A different coordinate system. The model arrives in its own space and has to be moved before it can be used with anything else.
• No acceptance check. Without a deviation report, there is no objective way to accept or reject the delivery.

Next steps before you commission a scan

• Write a one-sentence purpose for the model and share it with every consultant.
• Mark the extent on a plan, including what is excluded.
• List the element categories and give each an LOD and an LOA.
• Decide how hidden services will be handled.
• Agree the coordinate system and who sets the control.
• Name the software, version and file formats for delivery.
• Ask for the registration report and the model-to-cloud deviation report as standard.
• Keep the point cloud with the model, so later questions can be answered from the measured data.

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