Short answer: Scan-to-BIM turns a registered point cloud of an existing building into a BIM model. Its accuracy depends on scan coverage, registration quality, visibility and the tolerance agreed for the project.
Renovation, extension and facilities projects all start with the same question: what is actually there? Original drawings are often missing, outdated or wrong. Scan-to-BIM answers that question by using reality-capture data to build a model of existing conditions.
How it works
A surveyor captures the building with laser scanners or other reality-capture tools. Each scan produces millions of measured points. Scans from different positions are registered, or aligned, into a single point cloud. A BIM team then models walls, floors, openings, structure and services by tracing and fitting elements to that cloud.
- Capture: scans taken from multiple stations.
- Registration: scans aligned into one coordinate system.
- Review: coverage, noise and gaps assessed against the brief.
- Modeling: elements built to the agreed level of detail.
- Validation: the model is checked back against the scan.
- Delivery: model and related files handed over in the agreed format.
What affects the result
A model can only be as good as the data and the brief behind it. The main factors are:
- Coverage. Areas the scanner could not see are not in the cloud.
- Registration quality. Poor alignment shows up as doubled or shifted surfaces.
- Visibility. Furniture, ceilings and finishes hide what is behind them. Hidden conditions cannot be verified from scan data alone.
- Tolerances. The acceptable deviation between model and scan should be stated up front.
- Intended use. A model for space planning needs less detail than one for MEP coordination.
TipWrite down what the model will be used for before you specify its detail. It is the quickest way to avoid modeling too much, or too little.
What to prepare
When requesting a quote, share the point-cloud format and approximate size, registration information, reference drawings and photos, building type and purpose, disciplines and elements required, level of detail, software version, coordinate system and units, tolerances, naming conventions and target dates.
Where it is useful
Scan-to-BIM supports renovation design, as-built documentation, coordination of new work with existing structure and services, and facilities planning. It is most useful when the model scope and intended use are clearly defined from the start.