LiDAR
Distance measurement by laser light — the basis of nearly all precise 3D capture.
LiDAR stands for Light Detection and Ranging. The device emits laser pulses, up to millions per second in modern scanners, and measures how long the light takes to return. Travel time gives distance — and millions of such measurements give a point cloud.
The advantage over image-based methods: LiDAR measures actively and is therefore largely independent of lighting and surface texture. A dark cellar or a plain white wall is difficult for photogrammetry, but not for LiDAR.
The technology now appears in vehicles, drones and smartphones. Accuracy varies enormously: a phone’s LiDAR captures rooms roughly, a survey scanner works to the millimetre.