Tomographic approaches for airborne lidar bathymetry data processing

机载激光雷达测深是一种激光扫描技术，用于测量有限浊度的浅水水体的水体底部地形。由于新的传感器技术的出现，水深测量数据采集的空间分辨率大大提高，而且由于新的准则要求定期监测水体，这一专题最近变得具有相关性。激光雷达水深测量中的水下激光脉冲路径的特征在于与水浊度相关的衰减，恶化了数字化激光脉冲回波中的信噪比，从而阻碍了水体底部点的检测。该提案旨在开发基于相邻数字化激光脉冲回波的断层扫描表示的方法。在这些体素空间表示，一致的水体底部元素（而不是离散点）提取通过应用强大的参数估计和3D滤波技术。因此，预计将大大提高水体底部地形测量的精度和可靠性，从而也增加了激光雷达测深的潜在深度范围。此外，还应分析水柱中激光脉冲回波强度的衰减，目的是通过比较基于模型的衰减参数和实测衰减参数，得出描述水浊度的参数。除了传统的国家的最先进的机载激光雷达测深系统的数据，研究还将解决的适用性，开发的方法来处理最近的单光子机载激光雷达系统的数据。

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.