# Interaction in eXtended Reality Applications for Cultural Heritage
## 3 Related Work
### VR in Cultural Heritage  
Virtual Reality is a technology where the user should be completely immersed in a virtual environment without the visibility of a real environment, except through computer-generated representations [10]. A significant part of VR applications in cultural heritage has been accomplished with the use of 360\({}^{\circ}\) video [11; 12; 13; 14]. In [11], authors proposed motivational factor as a solution to the narrative paradox in presenting Sarajevo bridges. Using 360\({}^{\circ}\) video can be inexpensive, as shown in [12]. The application is displayed on a mobile phone with the use of Google Cardboard. The authors used time-pressure techniques and gamification to motivate users. In [13], the author described the framework for 360\({}^{\circ}\) video immersive applications. This framework was demonstrated in two case studies which showed that 360\({}^{\circ}\) VR applications can be effective in promoting areas of historical interest. The effectiveness of VR applications is shown in [14], where authors used electroencephalography (EEG) to evaluate the user's feeling of presence, immersion, and engagement with the experience of 360-video storytelling. The results showed high presence, engagement, and immersion in the participants. Strategies to overcome problems with the coordination and management of people involved in the process of creating a 3D reconstruction and its adaptation to Virtual Reality applications are described in [15]. The authors showed that one VR application can be made in four months, which includes data collecting, 3D scanning, 3D reconstruction and texture mapping, software development, and hardware design. However, there are a few very important things we must consider when VR is being used for storytelling. The VR experience comprises a lot of elements, and although we work with cultural heritage experts who can help us to shape the story and facts, we often find it hard to deliver content that is \"interesting\" for the regular visitor since their knowledge is vast, and it is hard for them to use only small pieces of it [16]. This can sometimes lead to the creation of a complex VR experience, with objects which do not have an actual story that users can follow. [PERSON] [17] actually suggested that \"Stories are about people, not things\", which should always be first priority when creating for the VR experience. This actually gave the research the fuel needed to strive forward. VR storytelling requires interdisciplinary groups to work together in creating a high-quality experience [18; 19; 20]. VR experience can be enhanced with the inclusion of characters and storytellers inside the VR space. They can be virtual humans or real-life actors. How to create quality virtual humans and their contribution to immersion are explained in [21]. On the other hand, real actors give a different level of immersion and add life to VR narration [22]. There are many feature creators who are trying techniques such as adding the footprints in this new media [23] to enhance immersion. Others aim for high-level precision when creating VR applications; for example, [PERSON] and his team combined different techniques such as \"media--real-time 3D visualization and HDRI panoramic photography--allows the interactive and immersive potential of the former to complement the high-fidelity and photorealism of the latter\" [24]. Through this, they explored how these different techniques could contribute to the VR experience. On the other hand, in a similar paper, [PERSON]'s team recreated the Al Zubarah Fortress in Qatar, which was then used to measure how demanding these models were for hardware, and how to smoothly integrate them without a drop in frame rate, etc. [25]. Some VR experiences do not require a story and can still provide an immersive feeling to a user, even if it is only an object from real life, scanned and imported as a 3D model [26].