vrtp Research Updatevrtp Research Update

Don BrutzmanNaval Postgraduate School

brutzman@nps.navy.mil

February 7, 2000

presentation outlinepresentation 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 protocolvirtual 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)•http://www.web3D.org/WorkingGroups/vrtp

vrtp goals for collaborative researchvrtp 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?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 componentsBamboo plugin components

•Hook it all together

•Dynamically extensible

•Kernel with callbacks

•Add plugins at runtime

•C++ and Java

•Examining XPCOM•http://www.npsnet.nps.navy.mil/Bamboo

•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):•Amaya http://www.w3.org/Amaya •Mozilla http://www.mozilla.org

Client 3D scene graphsClient 3D scene graphs

Clients for teleconferencingClients for teleconferencing

•University College London (UCL) tools

•sdr, vic, rat, wbd, nte•www-mice.cs.ucl.ac.uk/multimedia/software

ServersServers

•Apache•http://www.apache.org

•Jigsaw•http://www.w3.org/Jigsaw

•Currently all components are separate installs, automatic installation / update will be needed

Multicast peer-to-peerMulticast 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-vrmldis-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 browsersSimple is good!

Example scene: AUV in beach tanksExample scene: AUV in beach tanks

tracing entity behavior data in 3Dtracing entity behavior data in 3D

Capture the Flag demoCapture 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 Km2 terrain, Fort Irwin California• from Digital Elevation Model (DEM) database

•Runs across Multicast Backbone (MBone)

•Have almost reached design goal: fun!

dial-a-behavior protocoldial-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 architecturepacket-redefinition architecture

Protocol Protocol Definition Definition InterfaceInterface

Grammar Grammar parser builds parser builds replacement replacement

protocol protocol managermanager

MultiplayMultiplayer er

networkenetworked d

ApplicatioApplication Data n Data UnitsUnits

protocol protocol guruguru

SOIM - SOIM - Streams of Streams of

Interest Interest ManagersManagers

Shared 3D Shared 3D WorldsWorlds

XML

dial-a-behavior example 1dial-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 2dial-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 excerptdabp example XML excerpt<?xml version="1.0"?>

<!DOCTYPE PROTOCOL_DESCRIPTION SYSTEM "file:////vrtp/dabp/protocols/protocol_description.dtd">

<PROTOCOL_DESCRIPTION>

<FIELD_PRIMITIVE>

<FIELD_NAME>arrayCount</FIELD_NAME>

<FIELD_TYPE>org.web3d.vrtp.datatypes.UnsignedByte

</FIELD_TYPE>

<FIELD_DEFAULT>5</FIELD_DEFAULT>

</FIELD_PRIMITIVE>

<!-- etc. -->

</PROTOCOL_DESCRIPTION>

Many XML tools are available Many XML tools are available

Note that Note that validating validating XML tools XML tools

don’t permit don’t permit construction construction

of invalidof invalidtagsetstagsets

dial-a-behavior dial-a-behavior protocol is protocol is

part of vrtp’s part of vrtp’s streaming streaming

behaviors stackbehaviors stack

Eye-test charts Eye-test charts also availablealso available

Network monitoring & RTPNetwork 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•http:www.web3D.org/WorkingGroups/vrtp

Network monitoring & RTPNetwork monitoring & RTP

outlookoutlook

•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

contactcontact

Don Brutzman

brutzman@nps.navy.mil

http://web.nps.navy.mil/~brutzman

Code UW/Br, Naval Postgraduate School

Monterey California 93943-5000 USA

+1.831.656.2149 voice

+1.831.656.3679 fax