The short answer
If you need to measure a building's interior, structure or building services, use a terrestrial laser scanner. If it is open ground and you want an orthophoto, drone photogrammetry. If it is wooded terrain, linear infrastructure or textureless surfaces, drone LiDAR. On large assets, the norm is to combine two of them on the same coordinates.
The rest of this guide explains why, and which questions to ask before requesting a quote. For the detail of each technique, see what is LiDAR, what is photogrammetry and what is a point cloud.
The three technologies in one sentence
- Terrestrial laser scanning (TLS): a tripod-mounted instrument measures millions of points per station with its own laser. It is the most accurate and the slowest per unit area. Its mobile variant, SLAM, scans on the move: less accurate, much faster over long routes.
- Drone LiDAR: the same laser principle, from the air. Part of each pulse passes through the vegetation and reaches the ground, so it captures the terrain beneath the trees.
- Drone photogrammetry: calculates geometry from overlapping photos. It emits nothing; in exchange it gives the best colour and an orthophoto.
The five deciding criteria
1. What needs measuring: vertical and interior, or surface
Façades, interiors, structure, building services and everything under a roof are seen well by a terrestrial scanner and poorly by a drone. Terrain, roofs, quarries and plots are covered by a drone in a fraction of the time. This is the first split, and it almost always settles half the problem.
2. What is on top of the terrain
If there are trees, scrub or riverside vegetation and you need the ground, photogrammetry will not work: it only sees the canopy. Drone LiDAR records several returns per pulse and gets the terrain between the leaves. The same goes for smooth or textureless surfaces (metal-sheet roofs, uniform levelled ground), where photogrammetry cannot find common points between photos.
3. Size and shape of the area
With drone photogrammetry we cover up to 400 ha in a day, and with drone LiDAR up to 600 ha. The terrestrial scanner advances station by station: unbeatable on a building, inefficient on several hectares of terrain. A long, narrow corridor (road, canal, power line) favours drone LiDAR.
4. What accuracy you really need
The terrestrial scanner reaches ±2 mm nominal; a drone, 2-3 cm with ground support. For a Scan to BIM of building services or dimensional control of a structure, the difference matters. For a DTM, contour lines or an earthworks volume calculation, 2-3 cm is more than enough, and asking for millimetres only makes the job more expensive.
5. Which deliverable you need at the end
Start from the end: an as-built BIM model calls for terrestrial scanning; an orthophoto, photogrammetry; a terrain model under vegetation, LiDAR; a photorealistic virtual tour, perhaps Gaussian Splatting. The technology is chosen by the deliverable, not the other way round.
What fits each type of project
| Project | Recommended technology | Why |
|---|---|---|
| Existing building, refurbishment or Scan to BIM | Terrestrial laser scanning (SLAM in homes and small premises) | Interiors, structure and building services in millimetre detail |
| Façades and roofs | Terrestrial scanner + drone | The scanner covers the vertical; the drone, the roof that cannot be seen from the ground |
| Industrial warehouse or plant with services | Terrestrial laser scanning | Pipework, structure and equipment that a drone cannot see |
| Open plot, quarry, earthworks | Drone photogrammetry | Fast, economical per hectare and with an orthophoto |
| Wooded terrain, watercourses, slopes | Drone LiDAR | Captures the ground beneath the vegetation |
| Linear works: road, canal, power line | Drone LiDAR (+ terrestrial scanner on structures) | Covers kilometres of corridor and picks up cables and embankments |
| Galleries, tunnels, sewers | Terrestrial scanner or SLAM | With no open sky the drone adds nothing; SLAM speeds up long routes |
| Heritage and urban ensembles | SLAM or terrestrial scanner + drone | Geometry from the ground and roofs from the air, with real texture |
| Small plot, setting-out, boundaries | Conventional surveying (total station or GNSS) | A few specific points: mass capture does not pay off |
The last row is meant seriously: if what you need is to fix the boundaries of a plot or set out a footing, a surveyor with a total station will do it sooner and for less. We explain it in what is a topographic survey.
Comparison table
| Terrestrial laser scanning | Drone LiDAR | Drone photogrammetry | |
|---|---|---|---|
| How it measures | Its own laser, from a tripod | Its own laser, from the air | Geometry calculated from photos |
| Indicative accuracy | ±2 mm nominal (SLAM: 1-3 cm) | 2-3 cm with RTK or control points | ~5 cm; 2-3 cm with control points |
| Output rate | By stations: a building, a floor | Up to 600 ha in a day | Up to 400 ha in a day |
| Interiors and building services | Yes | No | No |
| Terrain under vegetation | Only in small areas | Yes, with multiple returns | No: it only sees the canopy |
| Textureless surfaces | Good | Good (water aside) | Poor |
| Light | Independent | Independent | Needs good light |
| Colour and orthophoto | Colour from panoramic photos | If a camera is added | Excellent, with orthophoto |
| Best for | Buildings, BIM, industry, tunnels | Wooded terrain, linear works, large areas | Orthophotos, quarries, open sites, roofs |
These are the indicative figures we work with. The real accuracy of each job depends on the equipment, the registration and the control points, and it is demonstrated with check points, not with the manufacturer's datasheet.
When to combine them
On large assets, choosing a single technology usually leaves gaps. Two examples from our projects:
- Retamares water tank (Canal de Isabel II): 83,000 m² with areas at height. Terrestrial scanning in the accessible areas and drone LiDAR for roofs and elevated areas, in a single combined point cloud.
- Urban heritage in Vigo (Vigo City Council): SLAM scanning with RTK at street level and a drone flight supported by ground control points, merged into a single high-resolution point cloud.
The condition for combining is that all captures share the same coordinate system, with common control points surveyed with RTK GNSS. Otherwise you will end up with several good point clouds that do not fit together.
What drives the cost
There is no price per square metre that works for comparing technologies, because each one scales with different things:
- Terrestrial scanner: the number of stations, which depends on the area, how many rooms and obstacles there are, and the level of detail required.
- Drone: the area, the vegetation, flight permissions and ground survey support.
- The deliverable: almost always the biggest line item. Modelling a BIM with building services or drafting a drawing with every element takes more hours than capturing the point cloud.
That is why, when comparing quotes, you should compare the same deliverable at the same accuracy. A low price for "scanning" that does not include registration, the accuracy report or the model is not comparable with one that does.
Common mistakes when choosing
- Asking for photogrammetry on wooded terrain: the result is the tree canopy, not the ground.
- Asking for millimetres where centimetres will do: scanning several hectares of terrain from a tripod for a DTM multiplies the timescale without improving the result for its purpose.
- Confusing resolution with accuracy: a very dense point cloud or a fine-pixel orthophoto can still be shifted. The figure that counts is the one from the check points.
- Choosing by technology rather than by deliverable: decide first what you will do with the result (BIM, drawing, DTM, measurement, virtual tour).
- Combining captures without a common reference: if the drone and the scanner do not share control points, the merge is done by eye.
How to decide with us
At LAURIA ESCÁNER we work with all three technologies, so we have no reason to push you towards any of them: terrestrial laser scanning and SLAM, drone LiDAR and drone photogrammetry, with RTK GNSS survey support so everything is georeferenced. We are a drone operator registered with AESA, the Spanish aviation authority; the registration is valid in every EASA state, and outside Spain we obtain permissions from each country's aviation authority. We are based in Madrid and work across Europe.
Tell us what needs measuring, what for and to what accuracy, and we will tell you which technology fits, or which combination, before we quote. Our services in detail: 3D laser scanning, drone LiDAR and drone photogrammetry.