## 5 Implementation
### Case Studies for Second Architecture: Collaborative Augmented Reality with the Use of a Smartphone  
For the second architecture, two different case studies based on smartphones were deployed, involving using three-dimensional objects collaboratively within a real environment. The creation of this applications is also based on the use of Unity [27, 28]; unlike the previous case, the edge part manages the spawning of objects and interactions with them. For collaboration, the devices will use the local network to create a \"room\", thanks to which each client will communicate to all room members, through P2P [29] messages, the positions or movements of an object. Once the user selects an object, the activated edge component is in local storage. At this stage, an initial request is sent to the local storage, which searches its Docker volume [30].The local storage contains previously downloaded objects from the cloud and sends them directly to the client for use if the object is already present. If, on the other hand, the object is not available locally, a new request is generated for cloud storage based on Firebase. The cloud storage system is structured through key-value logic, optimized to speed up the search for and retrieval of needed items. Several users tested the applications by downloading an APK file to their Android devices, allowing them to experience them on their own. For iOS devices, on the other hand, users had to go to dedicated booths, where the application was built directly from a PC to enable its installation and use. This approach ensured a smooth and customized experience for both operating systems. Two separate applications were developed. The first, created for the \"We Make Future\" fair in Bologna, Italy, at the MiC (Ministry of Culture) booth and illustrated in Figure 12, allowed multiple users to interact with shared virtual objects. The second application, presented as a prototype at an exhibition at the Central State Archives in Rome, was later deployed to enable use in a collaborative scenario, where participants could browse several digitized historical volumes collaboratively. Figure 11: Screenshot of the application in operation, deployed on the first architecture, with three different users connected. Through its hand reconstruction, one of them interacts with the shared objects within the scene, specifically the cubes. Case Studies for Third Architecture: Collaborative Hybrid Virtual and Augmented Reality with Use of Headset  
Finally, for the third architecture, two separate applications were developed and deployed, both characterized by the fact that most of the processing is shifted to the edge, using visors that handle real-time tracking of users' head and hand movements. In the first case, the main goal was to create an augmented reality (AR) experience by overlaying virtual elements on top of the real-world video stream users perceive. For this project, the library _MixedRealityToolkit_[31] provides an integrated framework for handling advanced inputs such as gestures and spatial interactions. This framework enables the development of immersive experiences without programming basic functionality from scratch. The scenario implemented (depicted in Figure 13) involves each user viewing, via his or her viewer, a combination of the real environment and an overlaid virtual layer when the application is started. The latter contains various interactive objects that can be shared and manipulated collaboratively among multiple users. In addition, each participant can move freely within their physical space, and their position and movements are represented to other participants in the room through virtual avatars. This system promotes interaction and collaboration in an enriched environment where physical and virtual reality merge. In the second case, an AR application was built and deployed that allows users to interact with both NPC (non-player character) avatars and other connected users (clients).