What is terrestrial laser scanning?

Terrestrial laser scanning (TLS) is static scanning from a tripod. The scanner stands still, measures millions of points from that position, and is then moved to the next setup. The setups are tied together into one point cloud. Because the instrument does not move while measuring, TLS gives the highest accuracy, down to ±1-2 mm.

How is mobile SLAM different?

A SLAM scanner is carried through the building at walking pace. It maps the surroundings and tracks its own position at the same time, so no tripod setups are needed. That makes it far faster over large areas: 20,000-30,000 m² per day while the facility stays in operation.

Which one is more accurate?

TLS. Static scanning reaches ±1-2 mm on the detail you point it at. Mobile SLAM is accurate enough for as-built documentation, quantity take-off and coordination, but it does not match TLS on a single critical detail.

Can the two methods be combined?

Yes, and on larger projects that is usually the right answer: mobile SLAM for the whole building or site, terrestrial laser scanning for the parts where tolerances are tight. Both end up in the same coordinate system and are delivered as one dataset.

What do we get delivered?

Point cloud, CAD or BIM, and a measurable model that opens in the browser without a plugin, the same deliverables regardless of which capture method was used.

Terrestrial laser scanning vs mobile SLAM

Two capture methods dominate reality capture of buildings and infrastructure: terrestrial laser scanning from a tripod, and mobile SLAM carried through the space. They are often presented as competitors. In practice they answer different questions, and the choice comes down to what your tolerances are and how much area you have to cover.

Terrestrial laser scanning (TLS)

The scanner is set up on a tripod and stays still while it measures. Nothing moves during capture, which is exactly why the accuracy is so high, down to ±1-2 mm. Each setup covers what it can see, so the operator moves the instrument around the space and the setups are registered into a single point cloud afterwards.

The trade-off is time. Every setup costs minutes, and complex geometry needs many of them. TLS is the method when tolerances are tight and the area is limited: a plant room, a facade detail, a machine foundation, a structural connection that has to be verified against the drawing.

Mobile SLAM

SLAM stands for Simultaneous Localization and Mapping. The scanner maps its surroundings while continuously tracking its own position, so it can be carried through the building at normal walking pace. No tripod, no setups, no repositioning.

That changes the arithmetic completely: 20,000-30,000 m² per day, with the facility still in operation. Nobody has to be moved out of the way and nothing has to be shut down. It also makes it realistic to rescan the same space several times during a project instead of once at the start.

Side by side

Accuracy: TLS ±1-2 mm. Mobile SLAM is sufficient for as-built documentation, take-off and coordination, but not for a single millimetre-critical detail.
Area per day: Mobile SLAM covers 20,000-30,000 m². TLS is measured in rooms and setups, not in hectares.
Disruption: Mobile SLAM runs while the operation continues. TLS occupies each position for as long as the setup takes.
Best for: TLS for tight tolerances on a limited area. Mobile SLAM for whole buildings, sites, tunnels, garages and portfolios.
Deliverables: The same either way, point cloud, CAD or BIM, and a measurable model in the browser.

How to choose

Start from the tolerance, not the technology. If a decision in the project depends on a millimetre, that part is scanned with TLS. If the question is what the building actually looks like today, layout, volumes, installations, what was really built versus what was drawn, mobile SLAM gives you the whole picture in a fraction of the time.

On most projects of any size we combine them: mobile SLAM for the whole, terrestrial laser scanning for the points that demand it. Everything lands in one coordinate system, so the recipient gets one dataset rather than two deliveries to reconcile.

Where this shows up in practice

On a construction project the capture becomes the as-built basis and can be sent along with the tender documents. On facility operations it means inspecting without shutting anything down. In both cases the deliverable is the same: a measurable model anyone can open with a link.

See what we deliver for construction and property→

Not sure which method your project needs? Tell us about the site and we will tell you.