Point cloud to Tekla: modelling existing steel where it really is

Most scan-to-BIM work ends up in Revit, because most of it is architectural. But when the project is structural steel — an extension hanging off an existing frame, new plant threading through a live building, screens going into an arena roof — an architectural as-built model is a translation problem waiting to happen. We model existing steel directly in Tekla, from the point cloud, because the next person who needs the model is a fabricator.

Why the destination format matters

A Tekla model isn't a picture of steel; it's fabrication data. Members carry profiles, grades and orientations; connections carry bolts, welds and plates; the model exports the drawings and NC files the workshop actually runs. When the as-built model lives in the same environment, new steelwork is detailed against existing steelwork in one model — interfaces, clashes and connection fit-up resolved where they're real, not approximated across a format boundary.

What the workflow looks like

The site is scanned — for us, with a Trimble X7 — and the registered point cloud is referenced directly inside Tekla. Existing members are traced through the cloud at the tolerance the job demands; where steel has settled, twisted or simply was never built to drawing, the model follows the building. On a recent stair package, that tracing discipline ran at roughly 2mm — tight enough that balustrades fabricated from the model fitted concrete that had never met its own drawings.

Where it earns its keep

The workflow pays for itself anywhere new steel meets old: connections into existing frames, infill structures, conveyor and plant supports, heritage structures where nothing is square, and live environments where a return site visit costs more than the survey did. The pattern in every case is the same — measure once, to the millimetre, and let the fabricator work to a model that tells the truth.