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N. Pfeifer:
"Lidar Principles and Airborne Scanning Lidar";
Keynote Lecture: ESF Exploratory Workshop, Heidelberg (invited); 2011-09-09 - 2011-09-10.

The concept Light Detection And Ranging allows the direct observation of the
range between a sensor and a target. This is exploited widely for the acquisition of
topographic information from airborne platforms, requiring additionally a scannning
mechanism and the observation of the sensor trajectory. Beyond the measurement
of the coordinates of 3d points, also geophysical parameters of the
reflect ing surfaces can be recorded exploiting the lidar principle. Ongoing and
possible developments will be presented, but also limitations of the technology.
The physical foundations will be laid out first. This concerns especially the formation
of the backscatter, i.e., the properties of the reflected signal. The properties
depend on the characteristics of the surface and the emitted signal including its
wavelength. The focus is, however, the impact onto the measured point cloud, contain
ing more than purely geometry. The developments in sensor technology indicate
the properties of "tomorrow´s" point clouds, leading to higher point density
and therefore enabling a wider range of applications. Also the properties of current
commercial state-of-the-art sensors will be presented. Finally, the quality of
the primary products of airborne scanning lidar will be discussed.