How accurate is the result?

No better than the scan, the alignment or the grid cell you pick. The figures describe the scan as it is placed in the scene, so a misaligned scan will look like a badly built wall. Align it first, and treat the result as a way of finding where to look.

What do the colours mean?

Green is within your tolerance of a model line, yellow is within three times the tolerance, and red is further away. Red is often furniture or people rather than a mistake, because a scan contains everything in the room.

Does it replace a survey report?

No. It has not been validated against a certified deviation analysis, and it works on a 2D slice rather than a 3D comparison. Use it to triage before paying for one.

No. The slice is computed in your browser, in a background worker. Up to 20 million points are sampled from a scan.

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Validation & quality · 2026-11-02 · 4 min

Check a Point Cloud Against the IFC Floor Plan, Without Scan-to-BIM Software

Is the wall where the model says it is? Slice the scan and the model at the same height and every part of the scan is coloured by its distance to the plan.

Plan of a point cloud slice in green, yellow and red according to its distance from the IFC floor plan

You have a laser scan and a model, and one question: was it built where it was drawn? The full answer takes specialist software. A first answer takes a slice through both at the same height.

Key takeaways

The slice is rasterised to a grid, so even a huge scan becomes a light sheet.
Each part of the slice is coloured by its distance to the plan cut from the IFC.
You get percentages, and a DXF or PDF to send.
It finds where to look. It does not certify anything.

Scan slice on top of the IFC plan, with the panel showing thickness, grid cell and tolerance — The CRAS Labs open dataset (Abreu et al., CC BY 4.0): a real as-built model and laser scan, loaded without manual alignment. Green and yellow follow the walls; red is what the model does not contain or what is out of line.

How to run the check

Load both Open the IFC and the scan in the viewer, and check that they line up in 3D.
Choose the slice In Drawings, Create, Plan from the scan, pick the level and height. A thin slice of about 10 cm at 1.2 m avoids floors and most furniture.
Set grid and tolerance A 2 cm cell and 3 cm tolerance are reasonable starting points for a building scan. Sparser scans need a larger cell.
Read the colours Green matches, yellow needs a look, and red is far from any model line. Turn the sheet off and on over the plan to see why.

Reading the numbers honestly

The percentages count grid cells, not wall length. Clutter inflates the red share, and only one height is checked, so a leaning wall can pass at 1.2 m and fail at 2.4 m. Run two or three heights if that matters.

The same slice works alone, with no model: it gives you a floor plan from a point cloud to trace over.

Check a Point Cloud Against the IFC Floor Plan, Without Scan-to-BIM Software