Ttime-of-flight 3D scanners use a laser pulse emitted and released through a rotating mirror. This pulse is reflected in the scanned surface and its reflection returns to the scanner. Measuring the time of return of the pulse is possible to calculate the distance, which is why they are called flying time. Depending on the degree of tilt and rotation of the mirror is possible to know the angle of incidence of the laser pulse, determining a position in a known Cartesian system x , y, z.
They are the most widespread in the documentation of the architectural heritage because of its versatility both for the long distance of acquisition and the quality and cleansing in the data collection. Usually they incorporate an integrated camera that provides the photochromic RGB value to each point adquired.