## 4 Results
### Virtual Reality Application  
Virtual reality represents an effective use of technology to visualize and interact with 3D reconstructions, as head mounted display (HMD) systems have become widely available and affordable. The use of immersive and interactive virtual reality systems reduces the distance barrier between the public, cultural heritage sites, and associated buildings and artefacts that often have been either destroyed, deteriorated, relocated, or even missing, as was the case of the looted Dacian ornamental disks reatriated in 2011, or the ones still being searched for by the Interpol.  
The developed virtual reality system application is intended for the Oculus Meta Quest 2. This headset is lightweight and represents an all-in-one system solution that can easily be packed and transported to indoor and outdoor museum exhibitions. This represents the perfect solution for outdoor events such as Open Day events at Sarmizegetusa Regia archaeological site, or even at the Dacian Hillfort from Piatra Rosie. Figure 23 presents an aerial view of the Sarmizegetusa Regia Sacred Area and various aspects from the Open Day Event organized directly within the archaeological site, with two large tents and a wide variety of digital equipment and applications.  
Figure 21: Interactive 3D database of the three currently available Dacian embossed disks.  
Figure 22: The 3D reconstruction of the two looted Dacian embossed shields.  
The virtual reality application was developed using the popular Unity engine, which is a cross-platform game engine capable of deploying a wide variety of digital applications mostly used for game development, but also widely used as the main platform for 3D cultural heritage applications. The solution can develop applications both for computers, consoles, mobile devices, web-based applications, virtual reality systems, augmented reality glasses, and mixed reality glasses.  
Since Meta Quest 2 represents a portable all-in-one virtual reality headset based on Android OS, the processing capabilities are limited when compared to a virtual reality headset that is directly connected to either a laptop, a computer, or that makes use of tethering capabilities. Since the application is intended for either indoor museum exhibitions or remote areas such as the Dacian Fortresses of the Orastiei Mountains archaeological site, where tethering technology is limited or there is no connectivity, the 3D application was highly optimized to integrate low polygon 3D models. The digital environment used within the application represents a 3D reconstruction of the Sarmizegetusa Regia Sacred Area (presented in Figure 24), which can be explored by using the teleporting functionality of the controllers. The Dacian embossed disks have been positioned on pillars, close to one of the temples to facilitate the ease of interaction.  
Figure 23: (**a**) Aerial view of the Sarmizegetusa Regia Sacred Area; (**b**) The two large tents used at the Open Day Event; (**c**) Visitor using an HMD system at the event.  
Figure 24: Overview of the VR application developed in Unity.  
Figure 25 presents three snapshots of the developed virtual reality application. The casting option of the Meta Quest 2 virtual reality system has been used to stream the output to a laptop where the screen has been recorded. The application can be used with ease to pick up, analyze, and interact with all of the five embossed disks that have been either 3D scanned or 3D reconstructed. For the fragmented disk, which represents the case study of this article, we have integrated within the virtual reality application both the current physical reconstruction and the proposed 3D reconstruction.