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W. Wagner, A. Roncat, T. Melzer, A. Ullrich:
"Waveform Analysis Techniques in Airborne Laser Scanning";
Keynote Lecture: ISPRS Workshop Laser Scanning 2007, Espoo, Finland (invited); 2007-09-12 - 2007-09-14; in: "IAPRS", XXXVI Part 3 / W52 (2007), ISSN: 1682-1777; 6 pages.

Small-footprint airborne laser scanners with waveform-digitising capabilities are becoming increasingly available. Waveformdigitising
is particularly advantageous when the backscattered echo waveform is complex because it allows selecting processing
algorithms adjusted to the task. In addition, waveform-digitising laser scanners depict the physical measurement process in its entire
complexity. This opens the possibility to derive the backscatter cross section which is a measure of the electromagnetic energy
intercepted and reradiated by objects. In this paper approaches for deriving the cross section along the laser ray path are discussed.
For data storage and processing reasons a practical approach is to model the waveform as the sum of a number of echoes
backscattered from individual scatterers. This approach involves estimating the number of echoes, finding a match between the
modelled echoes and the measured waveform, and estimating the cross section using calibration targets. For estimating the number
and position of echoes the Average Square Difference Function (ASDF) method, which is a discrete time delay estimation
technique, is tested. The results show that ASDF is a promising approach which appears to be less affected by noise compared to
more traditional echo detection methods.

LIDAR, Waveform, Analysis, Pulse detection, Decomposition, Deconvolution, Point cloud

http://publik.tuwien.ac.at/files/pub-geo_1936.pdf