A laser is an optical device that is capable of emitting short, intense pulses of monochromatic & coherent light. When such a laser pulse hits a remote object it is typically scattered in all directions, but a small fraction of the pulse energy is also scattered backwards where it can be registered by a photodiode. By measuring the round-trip time of the laser pulse the distance between the sensor and the object can be determined. By employing some kind of scan mechanism it becomes possible to sweep the laser beam over the surface of any object and, hence, to record the form of even the most complex objects; a technique known as "laser scanning".
Laser scanners can be operated on ground to scan building facades, statues or other objects. But laser scanners can also be mounted on airplanes and helicopters to survey large regions from above. Laser scanners are operated even on board of satellites to make global measurements of the earth's surface and atmosphere.
In recent years major technological advances have been made in laser scanning. Modern laser scanners acquire gigabytes of data in a matter of seconds. But before somebody can actually use these data they must be transformed into useful information. This is the scientific challenge of the Christian Doppler Laboratory for "Spatial Data from Laser Scanning and Remote Sensing". We develop methods to transform the raw laser scanner measurements into terrain-, building-, tree-, or power line models, which can subsequently be used in a diverse range of applications.
