Virtual Reality at Boston University

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

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

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. Distributed VR • Multi-person, multi-site shared virtual space • Navigation • Avatar representation • Telephony Scientific Computing and Visualizatrion

5. 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 Scientific Computing and Visualizatrion

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

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

8. 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 Scientific Computing and Visualizatrion

9. 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 Scientific Computing and Visualizatrion

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

11. 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 Scientific Computing and Visualizatrion

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

13. 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 Scientific Computing and Visualizatrion

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

15. 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 Scientific Computing and Visualizatrion

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

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

18. 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 Scientific Computing and Visualizatrion

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

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

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

22. 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 Scientific Computing and Visualizatrion

23. 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 Scientific Computing and Visualizatrion

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

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

26. Demonstrations • VR Bridging • ImmersaDesk • Display Wall Scientific Computing and Visualizatrion