Conference Agenda

This presentation introduces a digital twin and immersive VR system that reconstructs the “Hidden Foot” of Borobudur Temple in Central Java, Indonesia—an encased architectural layer containing 160 narrative bas-relief panels that cannot be directly observed today. The system integrates multi-source 3D point cloud data acquired via UAV and ground-level imaging with deep-learning–based 3D reconstructions of reliefs from historical monocular photographs and semantic segmentation results from previous work.

A custom passage model simulates the narrow gap between the original relief-bearing wall and the surrounding protective masonry, allowing users wearing a head-mounted display to virtually enter and walk through this otherwise inaccessible space. Within the VR environment, users can switch between photorealistic relief rendering and color-coded semantic overlays to support both immersive appreciation and analytical interpretation. A torch-based Level of Detail (LoD) strategy, driven by dynamic illumination, maintains high visual fidelity near the user while reducing rendering load for distant geometry, ensuring stable frame rates suitable for comfortable VR exploration.

A small user study indicates high ratings for visual realism, immersion, and the educational clarity of semantic overlays and gaze-triggered text annotations, highlighting the potential of this approach for research, documentation, and public engagement with hidden cultural heritage.

Three-dimensional (3D) scanning is widely used to preserve cultural heritage as large-scale point clouds. While these datasets contain rich geometric information, transparent visualization of such massive point clouds often suffers from visual clutter and reduced clarity, particularly when both external and internal structures are involved. Previous work resolved the problem of normal orientations, laying the foundation for robust shading in transparent visualization. Building on this foundation, this paper introduces a novel method of adaptive opacity control for region highlighting, which interprets shading as a distribution of opacity. By adjusting the lighting direction, effective opacity can be locally controlled without modifying the original point cloud data. This mechanism enables selective highlighting of user-specified regions, enhances the visibility of complex structures, while also allowing interactive dynamic shading by continuously changing the lighting direction. The effectiveness of the proposed method is demonstrated using culturally significant heritage point clouds, including UNESCO World Heritage sites, where intricate internal structures can be more clearly analyzed. Beyond cultural heritage, the proposed method is also applicable to modern architectural and other large-scale 3D scanned objects with similarly complex forms.

The concept of Digital Twin has attracted growing interest within research communities, including heritage conservation, in recent years. It combines detailed geometric documentation, real-time monitoring, and semantic information to create dynamic digital replicas of historic buildings. This paper presents the results of a scoping review of 204 peer-reviewed studies published between 2020 and 2025. The aim is to identify the main technologies, devices, and methods used to develop a Digital Twin for heritage buildings. The review reveals that terrestrial laser scanning (TLS), UAV photogrammetry, BIM, and IoT sensor networks form the core technological base. It also highlights the growing use of artificial intelligence for automated defect detection, predictive maintenance, and semantic processing. Based on the reviewed literature, the paper introduces a six-stage workflow for building a heritage Digital Twin, covering baseline documentation, static reality capture, semantic modelling, sensor integration, data fusion, and operational use. The findings show a clear shift from static 3D documentation toward dynamic, data-rich systems that support continuous monitoring and more informed decision-making. However, the review also identifies major challenges, including limited interoperability, complex data integration, incomplete AI validation, and long-term digital preservation issues. Overall, the study outlines the current state of Digital Twin technologies in architectural heritage and identifies key areas that require further research to support reliable and sustainable applications.

In the current context of energy and climate transition, the preventive conservation of historic buildings is particularly important due to their impact on architecture and works of art. Establishing the correlation between environmental variables and the condition of artworks in situ requires comprehensive and individualized monitoring, allowing for an understanding of cause-and-effect mechanisms. To address this challenge, the EPICO method provides a systematic framework for assessing deterioration risks in palace-museums through multi-scale monitoring and correlation between environmental parameters and object condition. The aim of the proposed topic is to enhance this decision-making tool with the creation of digital twins. These digital twins being fed with three-dimensional hyperspectral and LiDAR mapping of spaces and objects.