Optical 3D measurement techniques for generation, revision and monitoring of digital twins of complex building structures

光学三维测量技术为生成复杂建筑结构的数字孪生结构的几何和系统状态信息提供了有力的工具。到目前为止，这些方法的潜力，特别是数字孪生数据的更新和修订以及同时确定建筑物监测参数的潜力只得到了部分开发。在该项目中，将进一步开发、应用和验证光学3D测量方法，以有效生成精确的数字双胞胎3D数据。从图像或激光扫描仪数据中获得的3D建筑物表示将通过图像分析技术从相同的图像数据中获得的建筑物监测测量数据(如材料强度或裂缝模式)来丰富。作为基础，将使用传统的相机或激光扫描仪，无论是静态还是动态，包括无人机(无人机)作为传感器平台。基于这些图像和激光扫描仪数据，将通过现有的摄影测量技术生成密集的3D点云。在下一步，合适的数字孪生兄弟的几何结构，以CAD或BIM模型的形式给出，将适合这些点云。这允许完成、改进和修订不精确、不完整或错误的建筑表示。此外，还可以通过图像分析技术从图像数据中获得额外的建筑监测数据，如材料强度或高分辨率裂缝模式。通过图像数据的方位参数，这些监测数据可以直接转换到数字孪生兄弟上，方便用户进行数据解释。将特别注重从摄影测量图像和激光扫描仪数据中准确和可靠地确定材料强度，这需要改进摄影测量数据采集和处理计划，并特别注意大图像块中的误差传播。作为该项目的结果，将提供摄影测量方法，从而能够根据图像或激光扫描仪数据以及其他建筑物状态信息高效和精确地生成和修订数字双胞胎。

Optical 3D measurement techniques depict a powerful tool for the generation of geometry and system state information of digital twins of complex building structures. The potential of these methods, especially for digital twin data update and revision as well as for simultaneous determination of building monitoring parameters has only partially been exploited so far. In the project, optical 3D measurement methods for an efficient generation of precise digital twin 3D data will be further developed, employed and validated. 3D building representations obtained from image or laser scanner data will be enriched with building monitoring measurement data such as material strengths or crack patterns, obtained from the same image data by image analysis techniques. As a basis, conventional cameras or laser scanners will be used, which are either employed statically or in motion, including UAVs (unmanned aerial vehicles, ‚drones‘) as a sensor platform.On the basis of these image and laser scanner data, dense 3D point clouds will be generated by established photogrammetric techniques. In a next step, suitable geometric structures of a digital twin, given as CAD or BIM models, will be fit into these point clouds. This allows for the completion, improvement and revision of unprecise, incomplete or erroneous building representations. Moreover, additional building monitoring data, such as material strength or high resolution crack patterns, can be derived from the image data by image analysis techniques. Via the orientation parameters of the image data, these monitoring data can directly be transformed onto the digital twin, facilitating data interpretation by a user. Special focus will be put on the precise and reliable determination of material strengths from photogrammetric image and laser scanner data, requiring enhancements to photogrammetric data acquisition and processing schemes with particular attention to error propagation in large image blocks. As result of the project, photogrammetric methods will be available, which allow for an efficient and precise generation and revision of digital twins from image or laser scanner data, together with additional building state information.