ABSTRACT
Airborne laser scanning (ALS) is becoming a popular choice to determine surface elevation models. ALS systems integrate several surveying technologies. This chapter discusses the georeferencing component of an ALS. Georeferencing of light detection and ranging light detection and ranging (LiDAR) data requires the instantaneous position and attitude information of each range measurement. Direct georeferencing is the determination of time-variable position and orientation parameters for a mobile digital imager. The most common technologies used for this purpose are satellite positioning by global positioning system (GPS) and inertial navigation using inertial measuring units. The use of GPS data made block triangulation entirely independent of Ground control points. Only navigation and tactical grade gyros have been implemented in the georeferencing components of LiDAR systems. High- and medium-accuracy-grade systems can meet the accuracy requirements for LiDAR systems mounted on fixed-wing aircraft while low accuracy system can be adopted for low altitude helicopter based LiDAR systems.
