4. Scan Methods and Tools for Reconstruction of Built Environments as Basis for Digital Twins

A three-dimensional digital representation, as the Digital Twin of machines and objects within production plants, is becoming increasingly important for efficient planning and documentation of production. During the acquisition of the images, the two areas of accuracy and detail are key. The accuracy describes the precision in which the digital twin represents the real objects. For example, how well the dimensions of a machine within a reconstructed model matches its counterpart in reality. Detail refers to the level of detail in the digital model. Should the door of a machine tool be distinguishable from the machine or not. Two basic technologies have been established for scanning. The photogrammetry method creates a dense point cloud based on images using a sophisticated toolchain. The laser method firstly measures an accurate model of the environment using a laser scanner. In a second step, the color information is assigned to the measured points via the evaluation of photos. For certain applications, models resulting in highest accuracy and detail are not necessary; in these cases, speed and practicability of the acquisition is the primary concern. Due to recent advancements photogrammetry these methods are best suited in the case of generating a digital twin for production facilities. An overview of the methods available as well es the underlying principles is presented. Practical considerations and examples show the feasibility and results of different photogrammetry approaches, resulting in the presentation of a photogrammetric system well suited to the task of creating a digital twin of a production facility.