# A Review on Methods and Systems for Remote Collaboration
## 4 Visual Display Technologies
### 360-Degree Panorama View  
Another display option for collaborating remotely is the 360-degree panorama view, where the expert user can see all the surroundings of the local user. LiveSphere [88] is a remote collaboration solution that consists of a system with wearable camera headgear that provides 360-degree spherical images of the local user's surrounding environment. The headgear has six video cameras, and the video streams are fused into a spherical video that is transmitted to a remote user. This setup allows the off-site user to see the local user's view and also to have the freedom to look around via the on-site user's view. JackInHead [89] allows a local user to send an omnidirectional video to a remote user, who has an independent view of the local user's space. The prototype involves the use of headgear with multiple cameras worn by the local user and an HMD worn by the remote user. The omnidirectional video resulting from the images captured by the headgear is sent to the remote user, where it is mapped in a spherical virtual space. SharedSphere [90; 91] is a system used in interactive collaborations and allows 360-degree panorama video live sharing between two users. Hand gestures are overlaid on the live video; thus, mixed reality is used to enhance the collaboration. The guest user wears a VR HMD on which a high-resolution camera and a second 360-degree panorama camera are positioned. The video captured at the local site is sent to the host user, who wears a see-through HMD. The guest user can see the local user's hand gestures thanks to the video cameras, but the hands of the guest user need to be tracked with a hand-tracking sensor in order to be seen by the host user. [PERSON] et al. [92] proposed a remote collaboration solution that enabled the remote expert to have a 360-degree view of the remote environment while instructing the local user with the help of a projector equipped with a close-up attached camera and pointer capabilities. This setup allowed the expert to analyze the local user's environment independently. In contrast with other remote collaboration systems that offered a 360-degree view that allowed interaction between only two users, 360 Anywhere [93] allows multiple users to interact remotely by annotating a 360-degree video and projecting it back to the local users using AR. The remote collaborator has a total view of the local environment without the need for the local user to move or adjust the cameras. Besides adding annotations, the user can rewind the video, chat with the remote user, calibrate the system, and track the collaborator's gaze. On the Shoulder of the Giant [94] is a multi-scale mixed reality system sharing a 360-degree panoramic video that facilitates collaboration between a local VR user and a remote AR user. The study presents two modes of collaboration realized by the system: one shares a 3D reconstruction with the remote user, and the other shares a panoramic video at a different scale, using a 360-degree camera controlled by the remote user. Both users are allowed to switch between the two modes of collaboration. The use of the 360-degree camera was tested in different positions: head, back, hand, shoulder. The most preferred camera position was on the shoulder, which allowed the user to see the collaborator's face and environment. Table 2 shows the repartition of the articles and the display viewing technologies used in remote collaboration in the application field. It can be seen that, for maintenance, object manipulation, or other physical tasks, the visual display methods are important for both remote collaborators to have a clear view of the environment or the instructions that have to be followed. Similar to the previous section, in the following table, interested readers can easily and quickly identify the papers that address certain areas/tasks and the methods/equipment on which the solution of remote assistance/collaboration is based.