NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION OF WAVE PATTERN INDUCED COORDINATE ERRORS IN AIRBORNE LIDAR BATHYMETRY
NUMERICAL SIMULATION AND EXPERIMENTAL VALIDATION OF WAVE PATTERN INDUCED COORDINATE ERRORS IN AIRBORNE LIDAR BATHYMETRY
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DOI：
10.5194/isprs-archives-xlii-2-961-2018
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发表时间：
2018-05
期刊：
影响因子：
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通讯作者：
K. Richter;D. Mader;P. Westfeld;H. Maas
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作者：
K. Richter;D. Mader;P. Westfeld;H. Maas
抽象的。机载激光雷达测深(ALB)需要在空气-水界面进行基于斯内尔定律的折射改正，并对原始激光数据进行光速改正，以实现对水底的几何精确表示。严格地说，这需要对当地水面倾角有准确的了解。如果没有这方面的信息，就必须在校正方法中引入某些简化。通常的修正方法假定水面是水平的或局部倾斜的，同时假定有无限小的激光光线，从而忽略了有限激光脉冲直径穿透曲面的影响。在我们的模拟方法中，有限直径激光脉冲通过空气/水界面的折射是以严格的微分方式建模的。该模拟工具能够预测波致坐标误差，这些误差是由于常规折射校正方法中的忽略而不得不预期的。此外，从模拟揭示的误差的系统部分导出了与波型相关的校正项。本文的目的是对仿真工具预测的坐标误差进行实验验证。为此，对12×50米露天波池的机载激光测深数据进行了处理，并将结果与地面激光扫描获得的空池的参考数据进行了比较。对比结果表明，数值模拟预测的效果得到了实验验证。
Abstract. Airborne LiDAR bathymetry (ALB) requires a refraction correction on the basis of Snell’s law at the air-water interface and a speedof- light correction to be applied on the raw laser data in order to achieve a geometric accurate representation of the water bottom. Strictly speaking, this requires exact knowledge about the local water surface inclination. If this information is not available, certain simplifications have to be introduced in correction methods. Common correction methods assume either a horizontal or a locally tilted planar water surface as well as an infinitesimally small thin laser ray, thus neglecting effects caused by the finite laser pulse diameter penetrating a curved surface. In our simulation approach, the refraction of finite diameter laser pulses passing the air/water interface is modeled differentially in a strict manner. The simulation tool is able to predict wave induced coordinate errors which have to be expected due to the neglections made in common refraction correction methods. Moreover, wave pattern dependent correction terms were be derived from systematic portions of the errors revealed by the simulations. The goal of this paper is to experimentally validate the coordinate errors predicted by the simulation tool. For that purpose, airborne laser bathymetry data of a 12 by 50 meter open air wave pool were processed, and the results were compared to reference data of the empty pool acquired by terrestrial laser scanning. The comparison showed that the effects predicted in the numerical simulation are confirmed by the experimental validation.