Virtual Reality at Boston University Glenn Bresnahan Boston

Virtual Reality at Boston University Glenn Bresnahan Boston University Scientific Computing and Visualization (http: //scv. bu. edu/DAFFIE/BVRG-Talk-Mar 02)

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

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

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

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

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

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

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

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

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

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

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

DAFFIE Protocol l Objective – – l 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 13

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

DAFFIE Messaging System l Message router (“event server”) – Multiple delivery service classes • Globally sequenced, reliable delivery l 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 15

DAFFIE Messaging System l Proxy routers – Fan-in/fan-out l Tunneling – Direct routing for P 2 P Scientific Computing and Visualizatrion 16

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

VR/AG Bridging l 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 18

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

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

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

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

Tiled Display Wall l Prototype configuration – 2 x 2 stereo array (8 projectors) – 4 Linux display nodes + one control node – Fast Ethernet interconnect l Final configuration – – 4 x 3 stereo array (2 x 9. 4 Mpixel) 24 Linux display nodes + one control node 52 Linux compute nodes Myrinet interconnect Scientific Computing and Visualizatrion 23

Tiled Display Wall l Software – Wire. GL/Chromium – VTK – Performer + local synchronization – Movie player (several) Scientific Computing and Visualizatrion 24

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

Demonstrations l VR Bridging l Immersa. Desk l Display Wall Scientific Computing and Visualizatrion 26