Analysing the suitability of radiometrically calibrated full-waveform lidar data for delineating Alpine rock glaciers
Other literature type
With full-waveform (FWF) lidar systems becoming increasingly available from different commercial manufacturers, the possibility
for extracting physical parameters of the scanned surfaces in an area-wide sense, as addendum to their geometric representation, has
risen as well. The mentioned FWF systems digitize the temporal profiles of the transmitted laser pulse and of its backscattered echoes,
allowing for a reliable determination of the target distance to the instrument and of physical target quantities by means of radiometric
calibration, one of such quantities being the diffuse Lambertian reflectance.
The delineation of glaciers is a time-consuming task, commonly performed manually by experts and involving field trips as well as
image interpretation of orthophotos, digital terrain models and shaded reliefs. In this study, the diffuse Lambertian reflectance was
compared to the glacier outlines mapped by experts. We start the presentation with the workflow for analysis of FWF data, their direct
georeferencing and the calculation of the diffuse Lambertian reflectance by radiometric calibration; this workflow is illustrated for a
large FWF lidar campaign in the Ötztal Alps (Tyrol, Austria), operated with an Optech ALTM 3100 system. The geometric performance
of the presented procedure was evaluated by means of a relative and an absolute accuracy assessment using strip differences and
orthophotos, resp. The diffuse Lambertian reflectance was evaluated at two rock glaciers within the mentioned lidar campaign. This
feature showed good performance for the delineation of the rock glacier boundaries, especially at their lower parts.