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Outline

• Lab visits
• Geoff Bingham - Action Perception Lab - Wed, April 5, meet at 1:10 pm in Psych Building lobby
• Ray Burke - Customer Interface Lab - Thurs, April 13, meet at 4:55 pm in Business Building lobby
• Competition on Wednesday
• Collaborative VR & Visualization
• Credits & References
• Examples
• Issues

Credits & References

• Siggraph 99 Tutorial - Internetworked 3D Computer Graphics
• Siggraph 99 Tutorial - Developing Shared Virtual Environments
• Alliance '98 Tutorial by Andrew Johnson & Jason Leigh

 

Examples of Collaborative VR & Visualization

• MUDs and MOOs
• Web-based
• Proprietary Formats
• Active Worlds - http://www.activeworlds.com/
• Microsoft Virtual Worlds - http://www.research.microsoft.com/vwg
• VRML-based
• VNet (open source) - http://ariadne.iz.net/~jeffs/vnet/
• DeepMatrix (open source) - www.geometrek.com
• Blaxxun Community - www.blaxxun.com
• Parallelgraphics Islands - www.parallelgraphics.com
• General
• DIVE - lots of social issues studies in UK/Europe
• Sense8 World2World - www.sense8.com
• CAVERNSoft & LIMBO (EVL)
• Military Simulation
• SIMnet
• NPSNET - http://www-npsnet.cs.nps.navy.mil/npsnet/
• DIS-VRML-Java
• Engineering/Design Review
• Division's dVISE
• EAI/Sense8
• Visualization
• remote display in MVEs
• Virtual Director
• CAVE6D
• VizServing arrangement
• Medicine
• remote training
• remote consultation or procedures
• Business/Commerce
• ??
• Education
• Distance Learning
• Art
• performance, experiential art
• Gaming
• Doom, Quake, more peaceful pursuits
• 'nuff said

General Issues for Collaborative Environments

• Avatars
• 2D vs. 3D
• realistic vs. characatures
• articulated vs video - how much detail is needed
• exaggerated gestures in 3D
• pre-stored gestures
• distinguishing features or text names
• who's speaking?
• Audio
• most important communication channel for sense of co-presence
• very sensitive to latency and echo
• record & send vs. streaming
• Video
• video as a window, video as the avatar, video for avatar face
• benefits worth the network & hardware costs?
• problems with lighting in CAVE, HMDs?
• much more tolerant of noise and latency
• Network Characteristics
• Bandwidth - practical vs. theoretical throughput
• Reliability - UDP vs. TCP
• Latency - delay between event and perception of event, want to keep it low
• Jitter - variability in latency, want to keep it low
• multicast or point-to-point (unicast)
• Mbone  - multi-cast backbone - may save bandwidth at cost of cycles, must be configured at router level
• point-to-point topology: client-server, multiple servers <-- CAVERNsoft has gone from flexible topology to client-server exclusively
• What to send/how to send it
• transmit absolute instead of relative values
• transmit higher-level states instead of button presses or commands
• dead-reckoning in early military simulations
• use UDP for loss-tolerant stuff (e.g. avatar position, stuff which is sent frequently) <-- fallen out of favor for simplicity of single transmission protocol (TCP)
• use TCP for reliable state information
• lowest-common denominator (56K modem?)
• Persistence
• save state between sessions
• AI control - world continues to evolve in absence of users
• recording interactions
• avoid repeated downloads of large data sets
• Control
• turn taking / exclusive locks / baton passing
• no exclusion mechanism
• social cues - audio and avatars
• tethering - permission vs. request to attach
• asynchronous interaction - v-mail
• Web interfaces for
• casual collaboration
• monitor state of persistent worlds
• Scaling
• number of users
• size of data sets
• duration
• Security
• Frame rate vs. image quality vs. cost
• 8-10 FPS for animation
• content is king for level of engagement