VR volume rendering in image analysis provides a powerful and intuitive way to experience full volumetric rendering of image data. The depth perception and interaction possibilities of VR make it much easier to comprehend the relation between shape and function and to see how the spatial relationships between objects can affect our samples. However, communicating this increased understanding can be challenging when interlocutors don’t have access to the same tools. ZEISS arivis Pro VR offers a collaborative mode enabling multiple users to share the same virtual space thereby facilitating communication and collaboration when visualising 3D image data.

Collaborative sessions in arivis Pro VR work through a combination of tools and methods, the concepts of which may benefit from clarification.

Volume rendering for each user (locally)

This has several implications:

  • Collaborative VR requires that each user have their own workstation and arivis Pro VR license. It is possible to join a collaborative VR session without a headset although clearly the level of interactivity will be limited.
  • It is not possible for two users to join a session from the same workstation. This is largely precluded by the technical requirements of PC VR support. Indeed, at the time of writing no VR vendor supports simultaneous VR rendering for multiple headsets on a single workstation.
  • Enabling local rendering means that the data for each session is downloaded locally for each user and therefore:
  • Users need to ensure they have enough available local storage space to download the datasets for the sessions they wish to participate in.
  • Some time will be required to download the dataset locally before attending a session and the loading time will be dependent on the available download bandwidth and speed, and the size of the dataset.
  • The actual data exchange between the users during a session includes:
    • Volume position, scale and rotation within the VR space.
    • Volume rendering options such as rendering mode, opacity curves and channel visibility.
    • Information about the position of the various users’ locations and controllers positions for the purpose of rendering an avatar of these users within the virtual space.
    • Object filter settings, like selected object tags, clipping settings and active detail view ROIs.
    • Collaboration tool actions like the interactive pointer or the highlight sticker.

This approach ensures optimal performance by minimizing the data streaming requirements while limiting lowest common denominator issues (if one user has lower rendering quality due to GPU performance this does not affect the other users).

User roles and licensing

As with most modules of arivis software the collaborative module is license protected. The licensing dictates which arivis installations have the rights to create or edit collaborative session templates. While every basic VR license is sufficient to join a running session or start a new session from an existing template, the VR Collaboration Admin license is required to create or edit session templates. We can find out what modules are available and select the appropriate license accordingly by going to Help > Select License...:

Additionally, access to the collaborative server used to manage the sessions and users is managed through individual user accounts. User management, including creation of users and modifying of the login credentials is done through the collaboration server. Collaboration servers are managed by ZEISS arivis support. Contact ZEISS arivis support if you need to create or modify user accounts.

These are the main points of consideration concerning licensing and user access and roles:

  • A user account is required to access the collaborative panel and join a session.
  • Each session has its own participants list. Only users with existing accounts can be invited to participate in a session.
  • Any user who logs in to the collaboration panel on a computer with a VR Collaborative Admin license can create or edit session templates.
  • Any user added to the participants list can start or join a session.
  • The user who starts the session becomes the session owner and starts with the Presenter role.
  • Only one user can be presenter in a session at a time though the users can request the presenter role at any time and the presenter can cede this role over to any user who requests it.
  • The session owner can always reclaim the presenter role at any time from the session control panel.
  • Only the presenter can change the visualization parameters (rotation, scale & position of the volume, position of clipping planes etc).

With this in mind, let’s look at the various aspect of Collaborative VR.