Hansa Luftbild - German Air Surveys
P. O. Box 3609
Airborne laser scanning is especially developed for the acquisition of elevation data in large areas. In general, possible fields of application include the following (also in combination) :
The central instrument of the system is the Airbome Laser Terrain Mapper (ALTM 1020) mounted in a survey aircraft. This high. accuracy laser rangefinder scans beneath the aircraft to produce a wide swath over which the distance from the aircraft to the ground is measured and recorded. The sidewise deflection of the laser beam is also measured and recorded. Variable measurement frequency, scan rate, scan amplitude and flying height offer a high system flexibility, guaranteeing the best adaptation of the method to the respective terrain topography.
Two GPS receivers are used to locate the ALTM to within 10 cm. One receiver is installed onboard and the other is operated at a known ground position as a reference. Once gathered, the sensor positions along with the angles and distances determine the position of points on the earth's surface ("laser points"). These elements provide the database for deriving an accurate digital terrain model of the covered area with a very high density of elevations.
The accessibility to the height information, the production process, processing time, the flexibility of the method and cost-effectiveness are some of the aspects that put airborne laser scanning in favour of other methods of data capture for obtaining DTMS as well as new aerial mapping products.