AVATARS ON THE NET
Mitra
Chief Network Technology Officer
ParaGraph International
http://www.paragraph.com
http://www.mitra.biz
Avatars on the Net
- The Challenge
- History
- Human Problems
- Technical Problems
- Solutions
- The Future
THE CHALLENGE
- Merging Graphics with Online Services
- Working with what consumers have now
Merging Graphics with Online Services
- Online Services Brings
- Community
- Interactivity
- Dynamics
- Graphics Brings
Working with what consumers have now
- Pentium 90, 16Mb, SVGA
- 14,400 Baud Internet connection
- CD-ROM
HISTORY
- 1D (Text)
- 2D (Images)
- 2.5D
- 3D
1D - Text
2D - Images
- Habitat and Worlds Away
- Palace
2.5D - Restricted 3D
3D - Full 3D
- Black Sun
- AlphaWorld
- Online
- ParaGraph
- Military Systems
HUMAN PROBLEMS
- Suspend Disbelief
- High Expectations
- Rapid Response
- Rich Worlds
- Interactivity
- Flexibility Vs. Control
- Representing Yourself Online
Suspend Disbelief
- I'm in the Clouds by the Castle
High Expectations
Rapid Response
Rich Worlds
- Textures
- Objects
- Depth
- Lighting
Flexibility vs. Production
- Who builds the world
- Who changes the world
Representing yourself online
- Wide range of Avatars
- Different Avatars
TECHNICAL PROBLEMS
- Rendering
- Client bandwidth
- Server bandwidth
- Server power
- Security v. Flexibility
MORE TECHNICAL PROBLEMS
- Rapidly changing content
- Network quality
- '000s of Avatars
- Composability
Rendering
- Cannot render infinite polygons
- Rendering time vs. Quality
- Sprites vs. Polygons
Client Bandwidth
- Per Avatar per update: Id, Position, Orientation,
Velocity
- = (2 + 3 + 4 + 3) * 4 = 42 bytes
- Network Overhead ~ 30 bytes per packet for a
total of 72 bytes
- Sent 5 times a second = 360 bytes per avatar
per second
- 1000 avatars in the world = 360K bytes (3.6 MBaud)
per second PER CLIENT
Server Bandwidth
- Assume clients using half of 14,400 baud modem
= 7Kbaud
- 1000 clients, using 7Kbaud = 7Mbaud = 6 * T1
Server Power
- 1,000 users x 5 updates per second
- sorting ~ n^2
Security v. Flexibility
- Can a downloaded Applet edit your world?
Rapidly Changing Content
- Eats Bandwidth
- Loads servers
Network Quality
- 200 ms - 2 second latency
- 10% packet loss
'000s of Avatars
- Entering new rooms
- Download
- Memory and Disk
Composability
- Portable objects
- Debugging
SOLUTIONS
- Clever Protocols
- Sprites and Polygons
- Crowd Control
- Local Behaviors
- Modular Behaviors
- Distributed Servers
- CD-ROM *and* Net
- Mr Potato Head
Clever Protocols
DIS
- Not designed for people who pay for bandwidth
- Huge packets
- Military orientation
- Multicast
Multicast
- Not widely deployed yet
- Bandwidth ~ n
- Designed for static groups, not rapidly changing
- Designed for large groups, not small
Sprites and Polygons
- Optimize quality for rendering speed
Crowd Control
Local Behaviors
- Reduce network bandwidth
- Reduce latency
- D/D96
- VRML2.0
Modular Behaviors
- D/D96
- Flexible Event Structure
- Modularity
- VRML2.0
Distributed Servers
- Share the load
- Allow scaling to '000s of users
CD-ROM *and* Net
- Downloaded textures
- Some downloaded Geometry
- Changeable portions over the network
Mr Potato Head ®
- Kit of parts
- Repeated textures
FUTURE
Near
- '000's of simultaneous users
- Shared State
- Voice
- VRML 2.0
- CD-ROM's
VRML 2.0
- Cleans up VRML 1.0
- Adds Features
- Adds Behavior to VRML 1.0
Cleans up VRML 1.0
- Removes state from scene graph
- Changes geometry
Adds
- Sound
- Elevation Grids
- General Cylinders
- Sensors
- Interpolators
Behaviors
- Adds Behavior to VRML 1.0
- Supports behaviors in multiple languages
Further
- Replaces 2D on the Web
- Immersive
- ???
AVATARS ON THE NET
Mitra
Chief Network Technology Officer
ParaGraph International
http://www.paragraph.com
http://www.mitra.biz