You need to scan a building, a plant or a bridge, and the budget only allows for one device: a tripod-mounted terrestrial laser scanner (TLS) or a mobile SLAM scanner? Every surveying and engineering firm faces this question, and it is almost always framed the wrong way. There is no absolute winner. A TLS delivers millimetre-grade accuracy but multiplies setups; a SLAM scanner covers an entire floor in twenty minutes but its accuracy depends on the trajectory. The right choice follows from the project, not from the brochure. Here are the seven criteria that let you decide rationally - and avoid the two classic mistakes: paying for accuracy you don't need, or delivering data that falls short on a contractual survey.
Criterion 1: the accuracy you actually need
This is the fastest filter. A professional TLS achieves a ranging accuracy in the order of 1 to 5 mm, and a global 3D accuracy of 2 to 10 mm on a well-controlled project. A SLAM scanner offers a local accuracy of 5 to 20 mm, but its global accuracy can degrade to 1 to 5 cm on a long run without control points, due to trajectory drift.
So the right question is not "which scanner is more accurate?" but "what maximum error can my deliverable tolerate?". Industrial dimensional control (1 to 3 mm) demands a TLS. An office renovation (10 to 30 mm) or facility management (20 to 50 mm) are perfectly well served by SLAM. In between - detailed scan-to-BIM at 5-15 mm - the hybrid workflow rules.
Criterion 2: site size and complexity
A TLS only sees what is visible from its station. Every partition, machine or staircase creates occluded zones that require extra setups: a partitioned 2,000 m² building can require 40 to 80 stations - a full field day - while a SLAM scanner covers the same building in 30 to 60 minutes.
Conversely, on an open façade, an industrial hall or a large structure, the range of a TLS (typically 70 to 350 m, beyond 800 m for long-range models) becomes decisive, whereas most portable SLAM systems work between 25 and 120 m depending on the model. A simple rule: the more partitioned and occupied the site, the more value SLAM creates; the more open and accuracy-critical it is, the more the TLS prevails.
Criterion 3: turnaround time
Field time is only the visible part. Post-processing - registration, cleaning, modelling - routinely consumes 60 to 80% of the total project time. A TLS requires station-by-station registration: expect one to two office days for the 2,000 m² building above. A SLAM system produces a continuous trajectory, often pre-processed in the field, which sharply shortens the gap between site visit and deliverable.
If the client expects usable data within 48 hours and the tolerance is centimetric, SLAM almost always wins. If the deadline is comfortable and the tolerance tight, the TLS remains the safe choice.
Criterion 4: budget and total cost of ownership
Market price ranges overlap more than people assume: €20,000 to €70,000 for a handheld SLAM scanner, €20,000 to €70,000 for an entry or mid-range TLS, €60,000 to €120,000 for a high-end AEC TLS. Yet the sticker price says little about the real cost: software (€2,000 to €15,000 per year), maintenance (8 to 15% of the hardware price per year), training, calibration, storage.
Over three years, the total cost of ownership typically lands between €89,000 and €186,000 for an AEC TLS, and between €57,000 and €168,000 for a professional SLAM system. The difference is driven less by the technology than by the software ecosystem you commit to.
Criterion 5: your team's skills
A TLS calls for surveying culture: a station plan, targets, control points, residual-error management. SLAM looks simpler - you walk, it scans - but that simplicity is deceptive: walking speed, closing loops, handling feature-poor environments and validating before leaving the site directly determine quality. In both cases, the real bottleneck is usually data processing, not acquisition. A team without point-cloud skills will underuse any scanner you buy.
Criterion 6: the expected deliverables
A contractually binding survey - structural control, prefabrication, expert assessment - demands metrological traceability: targets, surveyed control points, a documented registration report. That is the TLS's natural ground. A feasibility study, an as-is capture, a BIM LOD 200-300 model or a cloud-shared collaboration base are produced faster and cheaper with SLAM. Always start from the deliverable: the scanner follows from the deliverable, never the other way round.
Criterion 7: how often you will use it
Below roughly twenty days of use per year, renting or subcontracting is generally more rational than buying. Between 20 and 50 days, it is a strategic trade-off. Beyond 50 to 80 days per year with a trained team, buying becomes defensible, then clearly profitable. An underused scanner is a cost centre; the same scanner embedded in a recurring service offer is a productive asset.
The 30-second decision guide
- Dimensional control, bridges, prefabrication: TLS, with control points.
- Detailed heritage documentation: TLS, with photogrammetry as a complement.
- Detailed scan-to-BIM (LOD 300+): TLS or hybrid TLS + SLAM.
- Office and retail renovation: SLAM is usually sufficient.
- Facility management, asset documentation: SLAM.
- Occupied sites (plants, hospitals): SLAM for circulation areas, TLS for critical zones.
- Tunnels, utility networks, GNSS-denied environments: SLAM with loops and control points.
- Large outdoor infrastructure: long-range TLS or vehicle-mounted mobile mapping.
The honest conclusion: the answer is often "both"
On complex projects, the 2026 standard is the hybrid workflow: the TLS sets the geometric reference on critical zones, SLAM rapidly covers circulation areas and large surfaces, and everything is consolidated in a common reference frame with documented quality control. Recent hybrid scanners, combining mobile capture with fixed acquisitions of a few seconds, confirm this convergence - without erasing the distinction between reference-grade accuracy and rapid capture.
These seven criteria give you the map. For the territory - detailed 2026 model sheets, independent benchmarks, priced TCO scenarios and quality protocols - our book Scanner 3D: TLS vs Mobile walks the full decision through, from the brief to the delivery.