Bridging BIM and reality: A hardware-optimized registration pipeline for Mixed Reality in indoor construction environments

Building Information Modeling (BIM) has transformed the Architecture, Engineering, and Construction (AEC) industry by digitizing project data, yet its full potential remains unrealized due to persistent gaps between virtual models and physical sites. These gaps contribute to inefficiencies, with studies reporting substantial waste in labor and coordination. Extended Reality (XR) technologies offer a promising solution by enabling immersive, real-scale visualization of BIM models on-site. This article introduces a Mixed Reality (MR) application for Microsoft HoloLens 2 that superimposes BIM representations onto construction environments at a 1:1 scale, supporting real-time detection of differences between the as-designed BIM model and the as-built construction on site. We present a robust registration pipeline that integrates commercial XR hardware with advanced algorithms to achieve precise alignment under challenging conditions. To validate the system, we conducted a controlled user study comparing three registration paradigms (manual gesture-based, QR-assisted, and fully automatic) and analyzing their impact on alignment accuracy and user experience (UX) in AEC-related tasks. Results show that our automatic approach provides advantages over state-of-the-art alternatives and significantly improves registration precision and usability ratings over the baseline methods. Furthermore, the study demonstrates that alignment errors strongly influence spatial perception and decision-making, highlighting the necessity of high-fidelity registration for effective MR integration in construction workflows.