LiDAR (Light Detection and Ranging) is a technology in the field of remote sensing that is capable of rapidly generating high-density, geo-reference digital elevation data with an accuracy equivalent to traditional land surveys but significantly faster than traditional airborne photogrammetric surveys.

In operation, a pulsed laser rangefinder mounted in the aircraft accurately measures the distance to the ground by recording the time it takes a laser pulse to reflect back to the aircraft from the ground or from objects such as building, trees or power lines. Since the speed of light is known, the elapsed time is converted to an accurate distance or slant range.

Some instruments record multiple returns from a single laser pulse to capture a verticle profile along the slant range. A scanning or rotating mirror to used to provide coverage across the path of the aircraft with swath widths dependent on scan angle and operating altitude. Simultaneously the inertial measurement subsystem records the roll, pitch and heading of the aircraft to determine its orientation in space, while the GPS subsystem provides the precise location of the aircraft.

During post-processing the orientation and GPS position solutions are combined with the laser slant ranges to calculate accurate XYZ coordinates for each laser return.