Virtual Reality at Boston University Glenn Bresnahan Boston University Scientific Computing and Visualization (

Virtual Reality at Boston Virtual Reality at Boston UniversityUniversity

Glenn Bresnahan

Boston University

Scientific Computing and Visualization

(http://scv.bu.edu/DAFFIE/BVRG-Talk-Mar02)

Scientific Computing and Visualizatrion 2

AgendaAgenda

Introduction to Access GridOverview of DAFFIE systemBridging between VR and AGTiled display wallsDemonstrations

3

Access Grid OverviewAccess 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


Distributed VRDistributed VR

Multi-person, multi-site shared virtual space– Navigation– Avatar representation– Telephony


DAFFIE OverviewDAFFIE Overview

Distributed Applications Framework For Immersive Environments

Component layers–Messaging system– VR protocol– Client applications (agents)

FOR MORE INFO...

http://scv.bu.edu/DAFFIE


DAFFIE Application ClientsDAFFIE Application Clients

ViewerSound server– Telephony generator– Sound player

Behavior agentsAudio/video generators/processorsObject generators/manipulators


DAFFIE EnvironmentDAFFIE Environment

viewerbehavior

agent

soundplayer

viewer

telephony

telephonysoundplayer

behavioragent

behavioragent event event

serverserver


DAFFIE ViewerDAFFIE 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


DAFFIE ViewerDAFFIE 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


DAFFIE Sound ServerDAFFIE Sound Server

Telephony generator– Digitize microphone input – Broadcasts "packetized" audio stream – Echo suppression


DAFFIE Sound ServerDAFFIE 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


DAFFIE AgentsDAFFIE Agents

Control object behaviorProximity triggersPortalsDevice interfaces– Kinematic sculptures

Video sourcing (camera)Audio and video processing


DAFFIE ProtocolDAFFIE 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


DAFFIE ProtocolDAFFIE Protocol

Compound objects– Geometry– Transformation– Audio hook– Video texture map

Component ownership/object locking– Request ownership– Broadcast changes– Release ownership

Ownership transfer


DAFFIE Messaging SystemDAFFIE 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


DAFFIE Messaging SystemDAFFIE Messaging System

Proxy routers– Fan-in/fan-out

Tunneling– Direct routing for P2P


DAFFIE Message routingDAFFIE Message routing

client

event event serverserver

client

clientproxyproxy

clientproxyproxy

client

client

client

client

client


VR/AG BridgingVR/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



Boston

Cyberarts

Festival

SC Global

FOR MORE INFO...

http://scv.bu.edu/hipart/GoGrid/



viewrenderer

audiorenderer

AG node

navigationvideobridge

DAFFIEDAFFIEMulticastMulticast

viewerAGaudio

AG node


Tiled Display WallTiled Display Wall

Benefits– Low cost– Scalable– Multi-use– Passive stereo

Construction– Linux cluster display driver– Inexpensive LCD projectors– Cheap polarizing filters



One or two Linux boxes per projector (plus control node)

Two projectors per tileLinear polarizing filtersPolarization-preserving projection

screenCustom fabricated projector mounts– 6 DoF adjusters



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



Software– WireGL/Chromium– VTK– Performer + local synchronization– Movie player (several)– Alignment

• Custom projector mounts• Computerized motor control• Imaging transformation warps• Autocalibration



Issues– Software– Alignment

• Custom projector mounts• Computerized motor control• Imaging transformation warps• Autocalibration

– Edge blending• Opto-mechanical• Software


DemonstrationsDemonstrations

VR BridgingImmersaDeskDisplay Wall

Virtual Reality at Boston University Glenn Bresnahan Boston University Scientific Computing and Visualization (

Documents

Virtual Reality at Boston University Glenn Bresnahan Boston University Scientific Computing and Visualization (