# Interactive Exploration of Virtual Heritage by Means of Natural Gestures
## 2 Related Work
One example of a large-scale digitization process of immovable cultural heritage is focused on the Klodzko Fortress [20], the authors have then made use of the point clouds acquired using 3D terrestrial laser scanning to define the virtual reality environment that presents the fortress. Since museums have started to digitize their inventory to enable web-based dissemination of their cultural assets, the next step involved the development of innovative and interactive museum exhibitions that would encourage some of the onlinevisitors to travel and visit the museum cultural heritage assets in real-life. This increased the demand of modern museum digital exhibitions to offer innovative interaction using natural gestures or with various immersive VR/AR systems, therefore creating an enhanced cultural exhibit experience. [PERSON] et al. developed a cultural heritage application that allows users to take the role of a sculptor and create Cycladic sculptures [21]. Other researchers combined Natural Interaction (NI) with AR to define interactive digital installations intended for cultural heritage. The proposed system integrates a low-cost HMD used for visualization and a Leap Motion sensor that tracks the user hands and allows the user to manipulate various 3D models of various archaeological findings [22]. While Leap Motion is focused on hand tracking, sensors such as Kinect can be implemented within museum exhibition to track both hand gestures as well as body gestures. A Natural User Interface was developed by [PERSON] et al. that makes use of the Kinect V2 sensor to enable various mid-air gestures for the navigation of virtual-tours in cultural heritage expositions as well as selecting 3D elements and zooming in and out within the scene [23]. A methodology of 3D scanning Intangible Cultural Heritage that integrates Kinect sensors was developed by [PERSON] et al. to precisely analyze the fingers of real dancers, to preserve intangible Cultural Heritage with the case study of Lazgi Dance [24]. This methodology is based on the same Natural gestures sensors that enable real time interaction with cultural heritage assets, but in this case, they are used to record real people dancing and recording the precise movement of both body and, most importantly, their hands. Digital storytelling by means of VR and AR technologies is the focus of [25]. Both a Kinect sensor and a Leap Motion sensor were used in order to detect gestures performed by users. The use of the Kinect sensor required users to maintain some static position to enable gesture detection and it was found to be \"too demanding for the users\", while the Leap allowed more free movements, while precisely detecting gestures. The educational potential of museums is enhanced by the use of VR, which allows gestural interaction with CH assets [26], using a Leap Motion sensor, coupled with an Oculus Rift. The advantages in terms of ease of the Leap Motion proposed it as the technological choice in this solution, and it was reinforced by the users' comments. Natural interaction achieved in immersive VR applications deployed in a museum setting was tackled in [27], in a comparison of the Leap Motion and Kinect sensor. The authors emphasized the appropriateness of using Leap Motion in an uncontrolled environment (such as a museum), as opposed to using the Kinect in a highly supervised and controlled environment. A complex technological system, encompassing a VR headset and a 3D tracking system, was developed for a cultural heritage setting in the Ara Pacis museum in Rome [28]. The VR and AR aspects of the exhibition were depicted to be among the focal aspects of interest for the users having minimal prior experience with VR, together with the exhibition content and the general organization of the museum. A hybrid VR-AR application for CH (cultural heritage) was investigated in [29], where authors also expressed their trust towards the ubiquity of the VR and AR in the near future.