A lidar scanner sends out a laser beam which is then swept across the subject as it spins along one axis. The lidar scanner records how long it takes for the laser beam to hit something and bounce back, known as the Time of Flight (ToF), or more specifically, lidar waveform. This lidar waveform represents a point in space and by accumulating thousands of these lidar points using a lidar scanner, a dense point cloud can be formed from all those individual lidar points that have been measured at different heights.
Lidar scanners are used extensively in aerial surveying where they spin on an axis while making a sweep across the object being mapped. In this process, each lidar point is assigned with x,y,z.
What is lidar
Lidar (LIght raDAR) works on the same principle as RADAR; lidar scanners emit ultraviolet, visible or near infrared beams.
The lidar waveform is what lidar scanners measure and this is the data that goes into producing a topographical map of an area. This lidar point cloud can then be manipulated to produce different kinds of maps like contour maps, hillshade map, point cloud density map etc.
As opposed to optical cameras where light bounces off objects onto photodiodes, lidar does not require any external lighting for it to work because lidars works with encoded laser beams which are pulsed out
What data do they create
Lidar scanners are specifically used for mapping or surveying purposes. Lidar scanners produce three dimensional data of the area being scanned which is in the form of lidar points, where each lidar point has x, y and z coordinates. The lidar scanner then uses these lidar points to produce a lidar point cloud that can be manipulated with software like ArcGIS, AutoCAD etc., to produce different kinds of maps. A lidar point cloud consists of 3D spatial data represented by lidar points that have x,y and z values assigned to them. This kind of data is generally used by civil engineers & architects to create digital elevation models (s), contour maps,
Why use a lidar for aerial survey
A lidar scanner is a high-end and expensive piece of equipment that only professionals would be able to use. Lidar scanners are used by civil engineers & architects for surveying purposes. These lidar scanners are mounted on helicopters, airplanes or other flying platforms which then capture data about the area being mapped in 3D space by lidar beams that are emitted from the lidar scanner.