BIM modeling of existing buildings - a study on effort and efficiency

In the project "FHprofUnt 2018: BIM Bauen im Bestand (BIM-BiB)", funded by the Federal Ministry of Education and Research, the campus of Trier University of Applied Sciences was surveyed using terrestrial laser scanners and the data obtained was transferred to BIM models of the campus buildings. Here, the efficiency of as-is surveys using 3D scanners, point cloud generation and post-processing, as well as BIM modeling of existing buildings is examined on the basis of the effort values obtained. The results show that the use of terrestrial laser scanners for as-is surveys is an efficient method, but the processing and creation of high-quality point clouds is still very time-consuming and the actual BIM modeling greatly exceeds the two first-mentioned work areas in terms of effort. To explain the results presented, the current state of the art and the project-specific problems are discussed. The data obtained and its evaluation reveal weaknesses in the efficiency of the methods available today and shed light on research opportunities to make the process of modeling existing buildings more economical.