Calibration of Laser Scanners

地面激光扫描仪（TLS）的精度降低了内部扫描仪失准（校准参数），其幅度大多超过随机偏差之一。在变形分析的背景下，这主要有两个结果：一方面，在两个时期的测量之间的差异d被系统偏差偏置。另一方面，系统偏差以类似的方式影响相邻点，这导致需要被并入随机模型fdd_dd中的测量之间的相关性。为了保证无偏的变形分析，必须校准系统偏差。因此，作为整个研究单元的一部分，该项目的目标是-减少系统偏差以获得无偏点云差异d -并推导出扫描仪校准参数的完全填充的方差-协方差矩阵，这是ESTA_dd的基本部分。TLS校准程序的进一步发展是基于无偏激光扫描仪的变形分析的关键之一，其目的是检测微小的几何变化。也就是说，校准与本研究单位提案中提出的几点高度相关：a）不考虑系统偏差，导致数据中的伪影，可能会使表面表示产生偏差; B）消除与仪器相关的系统偏差会增加灵敏度; c）校准不确定度的正确量化对于综合测量不确定度估计是必要的; d）系统误差的正确函数模型对于最佳仪器定位的无偏规划是必要的。

The accuracy of terrestrial laser scanners (TLS) is mitigated by internal scanner misalignments (calibration parameters) whose magnitude mostly exceeds the one of random deviations. This has mainly two consequences in the context of a deformation analysis: On the one hand, the differences d between the measurements at two epochs are biased by the systematic deviations. On the other hand, systematic deviations affect adjacent points in a similar way, which causes correlations between the measurements that need to be incorporated into the stochastic model Σ_dd. To guarantee an unbiased deformation analysis, the systematic deviations must be calibrated. Thus, the goal of this project as part of the whole research unit with the projects is to - reduce systematic deviations to get unbiased point cloud differences d - and to derive a fully populated variance-covariance matrix for the calibration parameters of the scanner Σ_cc, that is an essential part of Σ_dd. A further development of TLS calibration procedures is one of the linchpins for the unbiased laser scanner-based deformation analysis that aims at detecting small geometric changes. Namely, the calibration is of high relevance for several points raised in this proposal for a research unit: a) not-accounting for systematic deviations causing artifacts in data that can bias the surface representation; b) removing instrument-related systematic deviations increases the sensitivity; c) correct quantification of the calibration uncertainty is necessary for the comprehensive measurement uncertainty estimation; d) a correct functional model of systematic errors is necessary for unbiased planning of optimal instrument positioning.