Tomographic approaches for airborne lidar bathymetry data processing

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Airborne Lidar Bathymetry is a laser scanning technique to measure waterbody bottom topography in shallow waterbodies with limited turbidity. The topic has recently gained relevance due to the advent of new sensor technologies allowing for much higher spatial resolution in bathymetry data capture and due to new guidelines demanding regular monitoring of waterbodies. The underwater laser pulse path in lidar bathymetry is characterized by a water turbidity dependent attenuation, deteriorating the signal-to-noise-ratio in the digitized laser pulse echo and thus hampering the detection of waterbody bottom points. The proposal aims at the development of methods, which are based on a tomographic representation of neighbouring digitized laser pulse echoes. In these voxel space representations, consistent waterbody bottom elements (rather than discrete points) are extracted by applying robust parameter estimation and 3D filtering techniques. As a result, a significant gain in precision and reliability of waterbody bottom topography measurement is expected, thus also increasing the potential depth range of lidar bathymetry. In addition, the decay of the laser pulse echo intensity in the water column shall be analysed with the goal of deriving parameters describing water turbidity by comparing model-based and measured decay parameters. Besides data from conventional state-of-the-art airborne lidar bathymetry systems, the research will also address the applicability of the developed methods to processing recent single photon airborne lidar system data.