Static scanner or SLAM: when to use each
Both give you a point cloud, but they solve different problems. A short guide to choosing between them.
What each one does
A static (terrestrial) laser scanner sits on a tripod and measures millions of points from each position. You move it from station to station and then register the scans together, using targets, overlapping geometry or both.
A SLAM scanner (Simultaneous Localisation and Mapping) is carried by hand, on a pole or in a backpack while you walk. It works out its own position from what it sees as it moves, so it captures continuously instead of station by station.
When a static scanner is the better choice
- You need the highest accuracy and the least noise: facades, structural details, movement monitoring.
- The result has to tie precisely into a survey control network.
- Large open spaces, where a few stations cover a lot of ground.
When SLAM is the better choice
- Interiors with many rooms, stairs and changes of level: walking through is much faster than setting up dozens of stations, as long as there is enough geometry around for the system to keep track of where it is.
- You need quick, complete coverage and somewhat more noise than a static scan is acceptable, for example for space planning or early design work.
- Places where you cannot stay long.
Things to watch with SLAM
- Small errors build up over a long walk (drift). Close loops by coming back through areas you have already scanned and, where you can, include control points.
- It finds it harder to keep its position in long, uniform corridors, in wide open spaces and in areas with few features. These are the places to plan most carefully, or to support with control points or a few static stations.
- The cloud is noisier, so thin elements and fine details are harder to draw.
Combining both
On many building surveys the practical answer is both: static stations for the facades and key areas, tied to control, and SLAM for the interior circulation, registered into the same coordinate system. Check the overlap between the two clouds before you draw anything.
A simple rule of thumb
If the main question is how precisely, start with a static scanner. If it is how quickly and how completely, consider SLAM. Either way, check the cloud against a few independent measurements.