vrtp Research Update Don Brutzman Naval Postgraduate School February 7, 2000

presentation outline virtual reality transfer protocol (vrtp) bamboo & component architecture clients: 3D scene graphs dis-java-vrml dial-a-behavior protocol network monitoring outlook

virtual reality transfer protocol Enable large-scale virtual environments Provide network functionality via URLs because scene authors understand that Make networking “easy” for 3D graphics Supports many shared goals with Brown & National Tele-Immersion Initiative (NTII)

vrtp goals for collaborative research Implement general shared-behavior streaming mechanism for NTII Internetworked 3D graphics everywhere Design framework for Web-wide networked software architecture Provide mega content and connectivity for shared network experiences

what is needed on desktop? client looking at someone else’s world server showing others your world peer-to-peer multicast scalable behavior interactions network monitoring so that “everything just works” repeatable experimental environment

Bamboo plugin components Hook it all together Dynamically extensible Kernel with callbacks Add plugins at runtime C++ and Java Examining XPCOM

Many components in architecture

VRML 97 used for development Future: Java3D Extensible 3D (X3D) Fahrenheit Scene Graph Brown/NPS networked scene graph (NSG) Possible 2D browsers (for other apps): Amayahttp:// Mozillahttp:// Client 3D scene graphs

Clients for teleconferencing University College London (UCL) tools sdr, vic, rat, wbd, nte www-mice.cs.ucl.ac.uk/multimedia/software

Servers Apache Jigsaw Currently all components are separate installs, automatic installation / update will be needed

Multicast peer-to-peer Multicast Backbone (MBone) Multicast relay if not on MBone Behavior streams: many-to-many traffic Sensitive to latency and jitter more so than audio or video DIS: exemplar for dial-a-behavior protocol

dis-java-vrml VRML scene graph for entities Java for computation, network IEEE Distributed Interactive Simulation (DIS) Protocol: exemplar streamed behaviors Well defined, physically based Multicast networking Open source, web browsers Simple is good!

Example scene: AUV in beach tanks

tracing entity behavior data in 3D

Capture the Flag demo 6 tanks, 6 helicopters, referee for 2 flags Multicast peer-to-peer, no server Collision detection among entities, shots Terrain following locally by each entity 45 x 55 Km 2 terrain, Fort Irwin California from Digital Elevation Model (DEM) database Runs across Multicast Backbone (MBone) Have almost reached design goal: fun!

dial-a-behavior protocol Objectives Let applications customize protocols quickly Interpret new packet protocols at runtime General over-the-wire packet format Payloads defined using XML tags Java implementation in progress C++ XML parsers also available Used in vrtp streaming stack

packet-redefinition architecture Protocol Definition Interface Grammar parser builds replacement protocol manager Multiplayer networked Application Data Units protocol guru SOIM - Streams of Interest Managers Shared 3D Worlds XML

dial-a-behavior example 1 Write new protocol to carry a shared state variable of type “unsigned byte” Traditional approach is to write custom code, compile, link with app, debug Tedious, error prone, and especially difficult at runtime

dial-a-behavior example 2 dabp describes packet layout using XML dabp then parses, validates, and provides typed objects holding payload contents can access individual fields, update fields, serialize for network transmission ability to modify at runtime enables before-and-after testing if desired, add tags for content handlers

dabp example XML excerpt arrayCount org.web3d.vrtp.datatypes.UnsignedByte 5

Many XML tools are available Note that validating XML tools don’t permit construction of invalid tagsets

dial-a-behavior protocol is part of vrtp’s streaming behaviors stack

Eye-test charts also available

Network monitoring & RTP NPS thesis work by Francisco Afonso graduates September 1999 Uses Java Media Framework (JMF) 2.0 supports Real-time Transport Protocol (RTP) needed for native interface calls (e.g. IGMP) Provided comments to Sun JMF group, IETF Monitoring Information Base (MIB) Source now available via vrtp home page

Network monitoring & RTP

outlook X3D activity has preempted some efforts nevertheless vrtp work proceeds steadily on multiple component implementations will work on URLs second half 1999, first vrtp implementation by SIGGRAPH 2000 good matchup to CRCG research efforts, collaboration is mutually beneficial plenty of research and thesis projects

contact Don Brutzman Code UW/Br, Naval Postgraduate School Monterey California USA voice fax