Optimization of Terrestrial Laserscanning (TLS) Networks based on Sensitivity Analysis

基于灵敏度分析的地面激光扫描（TLS）网络优化

• 批准号: 536596365
• 负责人: Professor Dr.-Ing. Volker Schwieger
• 金额: --
• 依托单位: Institut für Ingenieurgeodäsie (IIGS)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/536596365?language=en
• 关键词: Optimization; Terrestrial; Laserscanning; TLS; Networks

Sensitivity analysis as understood in engineering geodesy usually deals with the ability to detect small deformations based on an assumed or expected deformation model (rigid body movements and distortions). In this project, deformations will be monitored by Terrestrial Laser Scanning (TLS) from different scanning sites (viewpoints). The challenge is to develop a multi-criteria optimization method for a first and second order geodetic design of a TLS network. This covers the number and positions of the viewpoints as well as the scanning settings (e.g. scan rotation velocity, angular resolution). The optimization should cover completeness and sensitivity. All this information can be provided in the planning phase for the viewpoint network. The developed optimization software should work for any given object geometry and any expected deformation. Assuring completeness means that all surfaces, edges and corners of the object are visible in the registered joint point cloud and sufficient overlap among the individual scans for registration is guaranteed. The completeness optimization using Greedy algorithms, mixed linear programming or metaheuristic approaches deliver a minimum number of TLS viewpoints together with their positions. This represents the initial solution for the optimization with respect to sensitivity. The objective function for the final optimization is the determinant of the covariance matrix in the direction of the deformation model. Therefore, the uncertainty of the object points acquired from each scanning site plays a substantial role. Here, scanning parameters like scan rotation rate and angular resolution, object-scanner distance and incidence angle, are considered. These parameters influence the sensitivity with respect to deformation models. A metaheuristic approach (e.g. genetic algorithms, simulated annealing) will be used for the sensitivity optimization. During the optimization procedure, the number of viewpoints and the spatial density of their possible positions are varied until the global minimum is reached. Since two optimization objectives may lead to a conflict, a number of possible (Pareto-optimal) solutions have to be provided. This target conflict may be further extended in case of additional objective functions (multi--dimensional case); e.g. by minimum time for scanning the network, thus a Pareto front of possible optimal-solutions is determined. Additionally, radar plots are created for decision support. In contrast to the research up to now, this project simultaneously aims at optimization with respect to minimal detectable 3D deformations and 3D completeness. Hence, a multi-criterial optimization will be investigated and a viewpoint planning tool will be developed.

在工程大地测量学中，灵敏度分析通常涉及基于假设或预期的变形模型(刚体运动和变形)来检测小变形的能力。在这个项目中，将通过地面激光扫描(TLS)从不同的扫描地点(视点)监测变形。挑战在于开发一种用于TLS网一阶和二阶大地测量设计的多准则优化方法。这包括视点的数量和位置以及扫描设置(例如扫描旋转速度、角度分辨率)。优化应包括完备性和敏感度。所有这些信息都可以在视点网络的规划阶段提供。开发的优化软件应该适用于任何给定的对象几何形状和任何预期的变形。确保完整性意味着对象的所有表面、边缘和角在配准的关节点云中都是可见的，并且保证用于配准的各个扫描之间有足够的重叠。使用贪婪算法、混合线性规划或元启发式方法的完备性优化提供了最少数量的TLS视点及其位置。这表示关于敏感度的优化的初始解。最终优化的目标函数是变形模型方向上的协方差矩阵的决定因素。因此，从每个扫描点获取的物点的不确定性起着很大的作用。在此，考虑了扫描转速和角分辨率、物镜距离和入射角等扫描参数。这些参数会影响对变形模型的敏感性。采用元启发式方法(如遗传算法、模拟退火法)进行灵敏度优化。在优化过程中，视点的数量及其可能位置的空间密度不断变化，直到达到全局最小值。由于两个优化目标可能导致冲突，因此必须提供许多可能的(帕累托最优)解。在附加目标函数(多维情况)的情况下，该目标冲突可以被进一步扩展；例如，通过用于扫描网络的最小时间，从而确定可能的最优解的帕累托前沿。此外，还创建了用于决策支持的雷达图。与目前的研究不同，本课题同时针对可检测到的最小三维变形和三维完整性进行优化。因此，我们将研究多目标优化问题，并开发一个视点规划工具。