Strict geometric modelling concepts for underwater laser triangulation

激光三角测量是一种最常见的光学三维测量技术，它基于激光光片在视差下照射相机成像的物体表面轮廓。该技术也非常适用于即将推出的uwv（无人水上车辆）上的3D传感器，用于对小河流的河床地形进行精确的水下测量，用于环境监测任务，以及其他水下测量任务。将激光三角测量技术应用于水下三维点坐标确定，需要对传感器的几何模型和随机模型进行多次修改，以进行建模和标定。因此，本提案的目标是建立一个严格的水下激光三角测量几何模型，并以UWV在环境监测领域的应用为重点对其进行验证。与通常在飞机上飞行的激光雷达测深仪器不同，激光三角测量系统可以设计成非常紧凑的低成本设备，可以很容易地安装在小型UWV平台上。它还具有比回声探测技术或机载激光测深技术更高的精度和空间分辨率潜力。与此相比，其有限的空间覆盖和深度范围的缺点在典型的UWV应用中就不太相关了，例如在提供河床数据作为小型集水区洪水模拟的基础，在生态系统监测，水下栖息地测绘或沉积过程监测中。除此之外，水下激光三角测量还为自动潜艇描绘了一个有趣的3D测量工具，用于管道焊接或水下考古等技术目的。

Laser triangulation, based on a laser lightsheet illuminating a profile of an object surface imaged by a camera under a parallax, is one of the most common optical 3D measurement techniques. The technique is also very relevant as a 3D sensor on upcoming UWVs (unmanned water vehicles) for precise underwater measurements of riverbed topography in small rivers for environmental monitoring tasks, as well as for other underwater measurement tasks. Applying laser triangulation techniques for 3D point coordinate determination underwater requires several modifications of the geometric and stochastic models for sensor modelling and calibration. Therefor the goal of the proposal is to develop a strict geometric model for underwater laser triangulation and to validate it with the focus on UWV applications in the field of environmental monitoring. Unlike lidar bathymetry instruments usually flown on an aircraft, laser triangulation systems can be designed as very compact lowcost devices, which can easily be mounted on a small UWV plat-form. It also has a much higher precision and spatial resolution potential than echo sounding techniques or airborne laser bathymetry. Compared to this, its disadvantages of limited spatial coverage and depth range are less relevant in typical UWV applications, which are for instance in the provision of riverbed data as a basis for flood simulations in small catchments, in ecosystem monitoring, underwater habitat mapping or in sedimentation process monitoring. Beyond this, underwater laser triangulation also depicts an interesting 3D measurement tool on autonomous submarine vehicles for technical purposes such as pipeline welding, or for underwater archaeology.