## 2 Background Knowledge
### VR Technologies in the Presentation of Artifacts  
There are elements of cultural heritage that either are not in a suitable physical condition (they cannot be directly exposed in various exhibitions and museums within the reach of visitors or the general public), or no longer exist (having disappeared but for which we have a series of clear historical evidence and functional replicas can be reconstructed), or are part of intangible heritage (legends, dances, songs, etc.). For all these cases, there are various approaches, all of them aiming to identify methods using new technologies that can enhance these artifacts. In this sense, the study from [23] can be highlighted, which aims, based on an in-depth survey on the use of VR technologies and new interaction paradigms, to increase the public's interest in cultural heritage. Thus, based on the characteristics of these methods in terms of interaction and immersion, it was aimed to achieve a clear classification of the technologies that can be used in this field, offering a tool for framing VR systems that suggests indications related to costs, usability, and quality sensory experience. A series of virtual reality components have been identified that can be successfully used in the presentation of artifacts. Thus, augmented reality, a technology that allows the user to see a combination of a mixed scenario generated by a computer, in which virtual objects are combined with the real environment, is being studied by several researchers [24]. In addition, for applications to present cultural heritage elements, in [25] and [26] multi-modal, mixed-reality technologies are used, which allow the real-time construction and interactive manipulation of photo-realistic virtual worlds based on real data sources. These applications have a high degree of interactivity and include provisions for other senses besides the visual (haptics and sound). However, several researchers considered that the sense of touch, in the case of studying or observing an artifact, brings an important added value. Therefore, there are several ways to approach the problem. In [27], it is proposed, before the construction of haptic equipment, to carry out a survey/studio to compare the experiences felt during the handling of a 3D-printed replica of the artifact with those experienced during the handling with the help of a gamified haptic interface based on the SUS scale and the AttrakDiff2 questionnaire. The obtained results showed that the proposed haptic interface is suitable for people who normally use mouse-based computer interaction, but without previous experience with haptic systems. An area very much covered by research is that of museums and the exhibition for visitors of functional replicas or digital interfaces based on VR technologies, includinghaptic feedback. Thus, in [28], a system is proposed that can be exhibited in \"Museum of Pure Form\" museums or displayed in a professional environment, such as CAVE. Other experts use for artifacts interfaces based on dedicated equipment (e.g., Sensable(tm) Omni 6 DoF, FALCON haptic device), which can be found on the market, developing only applications dedicated to specific artifacts whose digitally reconstructed 3D model is visualized on a computer display or in 3D glasses [29; 30; 31; 32]. Another direction of research is the complex study of some elements of intangible heritage, an example being the \"Gion Festival in Kyoto\" [33]. In this project, users can experience the things and events related to the Gion Festival with multiple virtual reality technologies, the interactive system being based on five human senses, such as the visual and haptic senses, the high-quality sounds of the festival music, and the virtual floating ceremony Yamahoko in the combined visual 3D environment. Consequently, it can be said that there is a tendency to study the components of cultural heritage using VR technologies, including mechanisms with haptic feedback.