From measured surfaces
to useful decisions.

01 / The starting point

Why measure an existing building?

Original drawings describe design intent. Renovations and field changes can leave today’s building looking different. A terrestrial laser scan records visible surfaces as a point cloud, giving your team a measured reference for the areas captured.

A 2010 research review published by NIST describes this gap between design models and as-built conditions, and the work needed to turn scans into building models. The distinction still matters when scoping a renovation: measurement comes first; interpretation follows.

At PRC, that starts with the question you need answered, such as a room’s geometry, a clearance, or the relationship between existing elements. Explore actual scan and model examples ↗

02 / Choose the useful output

A point cloud is not a finished BIM model.

A point cloud holds measured points. CAD drawings organize selected information into plans, sections, and details. A 3D model represents chosen elements at an agreed level of detail. Those are different deliverables with different amounts of development.

The same NIST review separates scan-to-BIM into geometry, object recognition, and relationships between objects. In practical terms, collecting points does not automatically identify every wall, pipe, or connection.

• Need spatial reference? Ask whether your software can use a registered point cloud.
• Need readable sheets? Define the plans, elevations, or sections required.
• Need design coordination? Agree which elements to model and the detail each needs.

Compare PRC deliverables ↗ before requesting more detail than the decision requires.

03 / Define the expectation

More points do not tell the whole accuracy story.

NIST’s 2011 study of 3D imaging range performance evaluated distance, angle of incidence, reflectivity, and target characteristics. Its findings support a practical lesson: measurement conditions matter alongside the instrument.

For a project, agree on critical dimensions, required tolerances, coverage, coordinates, and the deliverable review before capture. Blocked surfaces and inaccessible areas should be identified, rather than treated as measured geometry. Model detail and measurement accuracy should be discussed separately.

PRC uses terrestrial Trimble X9 scanning and scopes the workflow around intended use. See our equipment and accuracy approach ↗