Precision and Accuracy Evaluation of 3D Modeling in Indoor Confined Environments: Integrating Mobile Mapping System and BIM

With the increasing demand for 3D spatial data in engineering and geological applications, constructing practical 3D models efficiently and effectively has become a critical challenge in geology, underground engineering, and architectural documentation. In recent years, Simultaneous Localization and Mapping (SLAM) technology has been widely adopted in complex environments to collect high-density point clouds with high efficiency. However, the reliability and applicability of SLAM-derived results in geological and engineering contexts still require verification through practical case studies. This research utilizes the Building of the Civil Engineering at National Taipei University of Technology as the primary experimental site. A mobile SLAM system was employed to collect 3D point cloud data, which was subsequently integrated into the Building Information Modeling (BIM) framework—a standard in Taiwan's engineering industry—to assist in model construction and application. Furthermore, the study extends to several representative engineering and geological sites, including the Zhaishan Tunnel in Kinmen, the Kinmen Ceramics Factory, and the coastal rock outcrops at Qixingtan in Hualien, to explore the feasibility of SLAM-based 3D modeling under diverse environmental conditions.Regarding engineering applications, this study compares different positioning modes, including pure SLAM, SLAM combined with PPK, and SLAM integrated with RTK. Both absolute and relative accuracy at the architectural scale were analyzed using control points. Additionally, the impact of control point distribution on the geometric consistency of the models was investigated. These findings serve as a technical reference for selecting SLAM positioning strategies and operational workflows in engineering practice.In terms of geological and underground engineering applications, the research focuses on using SLAM point clouds for the 3D reconstruction and visualization of tunnel morphology, rock wall geometric features, and coastal outcrops. The results demonstrate the potential of this technology in tunnel geological recording, engineering planning, and outcrop preservation, providing a foundation for geological modeling in analytical tasks. In conclusion, this study proposes a practice-oriented workflow that integrates SLAM point clouds with BIM. By balancing engineering precision analysis with geological modeling applications, this research provides a high-efficiency 3D modeling solution with significant practical value for the architectural, tunneling, and geological sectors.