Abstract: In response to challenges in construction projects, such as the lack of transparency in concealed works and difficulties in tracing potential hazards during later stages, this paper proposes a method for synchronized perspective comparison between 720° panoramas and BIM models, developed based on a lightweight graphics engine. Firstly, the project's BIM model is constructed using Revit and converted into the L3M format via a self-developed lightweight graphics engine to achieve efficient web-based rendering. Secondly, 720° panoramic images are captured on-site using an Insta360 X5 camera and integrated into an online panoramic preview system developed with Three.js. Through secondary development of the lightweight graphics engine, dynamic linkage and bidirectional synchronization between the panoramic view and the BIM model perspective are achieved, establishing a visual comparison mechanism that ensures physical-digital consistency. After integrating this functionality into a smart construction site system, applications such as panoramic upload, reality-model comparison, and BIM/GIS hotspot association were implemented. Case studies demonstrate that, compared to traditional manual inspection, the proposed method reduces the average time required for quality issue communication and confirmation by approximately 30%, improves the efficiency of as-built documentation generation for concealed works by over 60%, and significantly enhances the fine-grained management of project quality and schedule, thereby providing robust technical support for intelligent construction practices.