Integrating Terrestrial Laser Scanning and 3D Gaussian Splatting for Heritage Building Documentation and Monitoring

Abstract. Accurate and reliable 3D documentation is important for the conservation and long-term monitoring of heritage buildings, where both metric precision and visual interpretability are required. This paper presents a co-registered hybrid 3D information model for heritage buildings, integrating Terrestrial Laser Scanning (TLS), Historic Building Information Modelling (HBIM), and 3D Gaussian Splatting (3DGS). The approach is demonstrated through a case study of Aula Timur ITB, a nationally protected heritage building in Indonesia. TLS data serve as the geometric backbone of the framework, providing survey-grade spatial reference. An HBIM model is generated from the TLS point clouds and structured using the Industry Foundation Classes (IFC) standard, ensuring that semantic building components are co-registered with the metric geometry. In parallel, a photorealistic 3DGS representation is generated from image-based reconstruction and rigidly aligned to the same TLS reference frame. Rather than producing a single fused geometry, the proposed integration results in a multi-layer representation in which metric, semantic, and radiance-field-based models coexist within a shared spatial reference. Quantitative alignment metrics, including transformation residuals, and cloud-to-cloud distance analysis, are used to assess geometric consistency between TLS and 3DGS. The integrated model is deployed in an immersive VR/MR environment to support intuitive navigation and visual inspection tasks. The results demonstrate that anchoring 3DGS to survey-grade geometry enables photorealistic real-time visualization while preserving spatial reliability, making the approach suitable for heritage documentation and monitoring scenarios. The proposed workflow highlights the complementary roles of metric surveying, information modelling, and emerging radiance-field representations in heritage-oriented 3D information systems.