3D LIDAR, or three-dimensional light detection and ranging, involves technology that emits light pulses that bounce off objects and return to the location of origin. Programs within the apparatus interpret returned signals as points in a designated area of space and transform these points into a 3D representation. Initially implemented by the military, 3D LIDAR imaging has a broad range of applications, including uses in the fields of archeology, geography and law enforcement.
The components of a 3D LIDAR imaging system typically include a laser, a scanner, a photo detector and a global positioning navigation system, or GPS. The laser sends thousands of light beam pulses to a mirror every second; the pulses then travel toward a particular location. The light beams used are generally in the ultraviolet, visible or close to the infrared wavelengths. When pulses contact an object, they reflect in various directions — a process known as back scattering. Many pulses of light, or the point cloud, return to the 3D remote sensing device, also called a photodetecting receiver.
The equipment typically records the time each pulse takes to travel to and from an object, or a location, as a specific point on a 3D axis representing longitude, latitude and altitude. The scanner uses this information along with 3D visualization programs to produce a 3D image. The greater the number of pulses emitted, the more dense and detailed the image becomes. Industries generally use 3D LIDAR technology to detect various sized substances from particles as small as gases and aerosols to solid objects or vast terrains, depending on the sensitivity and settings of the equipment involved.
With 3D LIDAR equipment mounted on a plane, 3D image maps and aerial photogrammetry are possible. Municipalities might use 3D city modeling to obtain accurate depictions of locations for purposes of construction planning, for security reasons or to enhance tourism. Animated LIDAR programs enable users to view images at various angles or varying light intensities. As light pulses pass through areas under certain conditions, environmental topographical images may be layered, starting with the land formation and continuing to the addition of water features and onto the tops of trees in forests.
Though generally mounted on a moving plane or satellite, the device also can be mounted in a static location and rotated, providing a 360-degree image of a specific location. 3D LIDAR technology also determines the speed of moving objects. Law enforcement use handheld devices that determine the speed of passing vehicles based on the time it takes for the light pulse to hit the object and return to the device.
