How accurate is 3D laser scanning?

What drives accuracy

Four factors determine the real-world accuracy of a scan: the scanner's specified accuracy at a given range, the distance to the surface being measured, the nature of the surface (reflective, dark or transparent surfaces scan less cleanly), and the quality of registration — how well multiple scan positions are tied together into one coordinate system. A high-end scanner with poor registration can produce a worse result than a mid-range scanner registered carefully.

Typical accuracy by capture method

Why registration matters as much as the scanner

A single scan only covers what's visible from one position. Capturing a full plant or vessel needs dozens or hundreds of scan positions, registered into one coordinate system. Errors accumulate if registration isn't controlled — through survey control points, targets, or overlap-based alignment — which is why registration and QA are as important to final accuracy as the scanner's raw spec.

Is that accurate enough for engineering work?

For as-built documentation, scan-to-BIM, clash detection and most integrity assessments, millimetre-to-low-centimetre accuracy is well within the tolerances engineers work to. Where tighter tolerances are needed — small parts, precision alignment — close-range scanning reaches accuracy an order of magnitude finer.

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