When a design team asks for a “scan-to-BIM model,” the conversation usually turns to accuracy pretty fast. You’ll hear numbers like ±1/8”, or phrases like “LOD 300,” or “6mm point cloud accuracy.” These terms mean different things, and mixing them up leads to scope gaps and budget surprises on renovation projects.
Here’s what each one actually means, and how they relate to each other on a real job site.
Point Cloud Accuracy vs. Model Accuracy
Point cloud accuracy refers to how precisely the scanner records physical space. A terrestrial LiDAR scanner like the ones we use captures points with accuracy in the 2–6mm range at typical interior scan distances. That number describes the raw data, not the Revit model that comes from it.
Model accuracy is a separate question. When a modeler traces walls, doors, and structural elements from the point cloud, they introduce decisions: where exactly does this wall face sit relative to the point cloud? How thick do we model that concrete column? The model is always an interpretation of the scan data, not a direct copy of it.
In practice, a point cloud captured at 3mm accuracy can support a model accurate to ±1/4” on most elements, and ±1/8” on elements where the geometry is clean and unobstructed.
What LOD Actually Specifies
Level of Development (LOD) is defined by the BIMForum LOD Specification and describes how much geometric and non-geometric information a model element contains, not how accurately it was measured. LOD 200 elements are approximate in size and shape. LOD 300 elements are modeled with specific dimensions and location. LOD 350 adds the connection geometry needed for coordination between trades.
For most renovation scan-to-BIM projects, LOD 300 is the right deliverable. It gives your design team enough information to produce construction documents and coordinate with engineers, without paying for detail that won’t affect the outcome.
LOD 400, which represents fabrication-level detail, is rarely appropriate for as-built documentation. If a subcontractor asks for LOD 400 from a scan, ask them to get specific about which elements actually need that level of detail.
Where Tolerances Break Down on Site
The hardest part of specifying accuracy on a renovation project is that existing conditions rarely cooperate. Walls are not plumb. Floors are not level. A concrete slab that’s been in service for thirty years may slope 3/4” across a 50-foot span. The scan captures all of that faithfully. The model has to make a choice.
This is where scan-to-BIM projects go sideways. A modeler who averages out an out-of-plumb wall to make it “cleaner” is discarding real information. A contractor who later frames a partition to the model dimension and finds a 1/2” gap at the existing wall isn’t dealing with a scan error; they’re dealing with a modeling decision that wasn’t communicated.
The fix is straightforward: the model should represent what is there, not an idealized version of it. Out-of-plumb, out-of-level, and irregular surfaces belong in the deliverable, with a note that the point cloud is available for reference on any element where exact field conditions matter.
The Accuracy Report
Every scan we deliver includes a point cloud accuracy report. It documents the registration error for the scan network, which is the measure of how well individual scan positions were tied together into a unified coordinate system. Registration error on a well-executed interior scan typically runs under 3mm.
This report gives your structural or MEP engineer a documented baseline. If there’s ever a question about whether a dimension in the model reflects what was actually there, the point cloud is the reference and the accuracy report tells you how much to trust it.
Frequently Asked Questions
What accuracy should I specify when requesting a scan-to-BIM?
For commercial renovation work, ±1/4” model accuracy at LOD 300 covers most design and coordination needs. If you have specific elements that require tighter tolerances, call those out individually rather than specifying tight accuracy across the entire model. It keeps scope realistic and cost predictable.
Does the scanner accuracy number apply to the Revit model?
No. Scanner accuracy describes the raw point cloud data. The Revit model is modeled from that data, and its accuracy depends on the modeler’s methodology and the clarity of the geometry being captured. Expect the model to be somewhat less precise than the underlying scan.
What if the existing conditions are irregular?
The scan captures them exactly as they are. How those conditions are represented in the model is a scope decision. Ask your scanning vendor upfront whether irregular geometry will be modeled as-found or simplified, and get the answer in writing before the project starts.
Can we use the point cloud directly instead of a BIM model?
Yes. Point-cloud-only delivery is an option, and for some projects it’s the right call. Design teams working in Revit or AutoCAD can reference the point cloud directly without waiting for a full model. We deliver in .rcp and .e57 formats, which are compatible with most major design platforms.