The disappeared Castle – The Return of the Horneburg in Virtual and Augmented Reality

Abstract. Technological advances in virtual reality (VR) in recent years have the potential to impact our everyday lives increasingly. VR enables us to explore a digital world through an immersive experience with a head-mounted display (HMD). When combined with tools for 3D documentation and modelling, as well as software for creating interactive virtual worlds, VR can play a significant role in preserving and visualising cultural heritage for museums, educational institutions, and other cultural sectors. VR opens up a new form of scientific communication that can benefit damaged, destroyed or distant historical and cultural heritage objects. On the other hand, augmented reality (AR) can resurrect and display forgotten and lost cultural heritage objects and monuments in their original locations via mobile devices. This paper presents the development of a VR and AR application of the disappeared Horneburg castle, which does not exist anymore since almost 400 years. These applications will serve as tourist attractions for visitors to the municipality of Horneburg, enabling them to experience the castle's historic life in an immersive way at the museum and interactively on site. Based on the uncovering of the underground remains of the castle by geomagnetic prospecting the Horneburg Castle was reconstructed using a derived 2D site plan and architectural drawings of the castle buildings. The 3D models of the buildings were constructed using the 2D drawings, which were then transferred to the game engine Unreal 5 for texture mapping and immersive visualisation. The AR app was developed to visualise the whole building ensemble with the wooden palisade around the castle or each individual building on mobile android and iOS devices using WebXR and Three.js on site in nature (option 1) and location-independent (option 2). The technical implementation of the VR and AR applications is presented in this article.