1. Virtual Reality at Boston University Glenn Bresnahan Boston University Scientific Computing and Visualization (http://scv.bu.edu/DAFFIE/BVRG-Talk-Mar02)

2. Scientific Computing and Visualizatrion2 Agenda Introduction to Access Grid Overview of DAFFIE system Bridging between VR and AG Tiled display walls Demonstrations

3. 3 Access Grid Overview Suite of commodity hardware and software –Open source, Open protocol Multicast Tiled projection wall Approximately 90 installations world-wide (7 countries) FOR MORE INFO... http://www-fp.mcs.anl.gov/fl/accessgrid/ http://scv.bu.edu/accessgrid

4. Scientific Computing and Visualizatrion4 Distributed VR Multi-person, multi-site shared virtual space –Navigation –Avatar representation –Telephony

5. Scientific Computing and Visualizatrion5 DAFFIE Overview Distributed Applications Framework For Immersive Environments Component layers –Messaging system –VR protocol –Client applications (agents) FOR MORE INFO... http://scv.bu.edu/DAFFIE

6. Scientific Computing and Visualizatrion6 DAFFIE Application Clients Viewer Sound server –Telephony generator –Sound player Behavior agents Audio/video generators/processors Object generators/manipulators

7. Scientific Computing and Visualizatrion7 DAFFIE Environment viewer behavior agent sound player viewer telephony sound player behavior agent behavior agent event server

8. Scientific Computing and Visualizatrion8 DAFFIE Viewer SGI Performer based Mono or stereo display Workstation, CAVE/Immersadesk, HMD Six-degree of freedom head-tracking Six-degree of freedom navigation Texture-mapped streaming video

9. Scientific Computing and Visualizatrion9 DAFFIE Viewer Simple "script-based" world description –Geometric models –Animation –Sounds Many 3D model formats Interaction by picking and/or proximity Local control of time-sensitive animation and sound Global update of avatar motion and object state

10. Scientific Computing and Visualizatrion10 DAFFIE Sound Server Telephony generator –Digitize microphone input –Broadcasts "packetized" audio stream –Echo suppression

11. Scientific Computing and Visualizatrion11 DAFFIE Sound Server Sound player input –Multiple sound sources Real-time audio streams (e.g. telephony) Prerecorded object sound files –Audio attachment objects (3D location) –Avatar position in virtual space –Listener position in physical space Sound player output –Multi-channel localized audio signals

12. Scientific Computing and Visualizatrion12 DAFFIE Agents Control object behavior Proximity triggers Portals Device interfaces –Kinematic sculptures Video sourcing (camera) Audio and video processing

13. Scientific Computing and Visualizatrion13 DAFFIE Protocol Objective –State consistency –Persistence –Equipotent clients –Network visible state Message (event) based –Message classes –Delivery service classes Globally sequenced, reliable delivery –Message class subscription

14. Scientific Computing and Visualizatrion14 DAFFIE Protocol Compound objects –Geometry –Transformation –Audio hook –Video texture map Component ownership/object locking –Request ownership –Broadcast changes –Release ownership Ownership transfer

15. Scientific Computing and Visualizatrion15 DAFFIE Messaging System Message router (“event server”) –Multiple delivery service classes Globally sequenced, reliable delivery Client application library (API) –Point-to-point and broadcast –Polled or callback (active messages) –Subscription based receive –Multithreaded, non-blocking –Services Registration, timing, synchronization, query

16. Scientific Computing and Visualizatrion16 DAFFIE Messaging System Proxy routers –Fan-in/fan-out Tunneling –Direct routing for P2P

17. Scientific Computing and Visualizatrion17 DAFFIE Message routing client event server client proxy proxy

18. Scientific Computing and Visualizatrion18 VR/AG Bridging Interconnect VR and AG spaces –VR image display over AG –Bridge audio in both directions –Provide interactivity for AG participants AG navigation AG interaction tools –Couple external a/v to both AG and VR

19. Scientific Computing and Visualizatrion19 VR/AG Bridging Boston Cyberarts Festival SC Global FOR MORE INFO... http://scv.bu.edu/hipart/GoGrid/

20. Scientific Computing and Visualizatrion20 VR/AG Bridging view renderer audio renderer AG node navigation video bridge DAFFIE Multicast viewer AG audio AG node

21. Scientific Computing and Visualizatrion21 Tiled Display Wall Benefits –Low cost –Scalable –Multi-use –Passive stereo Construction –Linux cluster display driver –Inexpensive LCD projectors –Cheap polarizing filters

22. Scientific Computing and Visualizatrion22 Tiled Display Wall One Linux node for every 1 or 2 projectors –One additional “control” or “head” node Two projectors per tile Linear polarizing filters Polarization-preserving projection screen Custom fabricated projector mounts –6 DoF adjusters

23. Scientific Computing and Visualizatrion23 Tiled Display Wall Prototype configuration –2x2 stereo array (8 projectors) –4 Linux display nodes + one control node –Fast Ethernet interconnect Final configuration –4x3 stereo array (2 x 9.4 Mpixel) –24 Linux display nodes + one control node –52 Linux compute nodes –Myrinet interconnect

24. Scientific Computing and Visualizatrion24 Tiled Display Wall Software –WireGL/Chromium –VTK –Performer + local synchronization –Movie player (several)

25. Scientific Computing and Visualizatrion25 Tiled Display Wall Issues –Software –Alignment Custom projector mounts Computerized motor control Imaging transformation warps Autocalibration –Edge blending Opto-mechanical Software

26. Scientific Computing and Visualizatrion26 Demonstrations VR Bridging ImmersaDesk Display Wall