Networked Virtual Environment intern midterm presentation

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Networked Virtual Environmentintern midterm
presentation
Implementation of Seamless MPEG-4 Streaming over
Mobile IP-enabled Wireless LAN
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Contents

• Basic concept of Networked Virtual Environment
• The introduction of IMRC project
• Virtual reality software
• CAVELib
• VR-Juggler
• The existing problem in Net-VE
• Future work

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Basic Concept of Net-VE

• Allow multiple users to interact in real-time
  with others around the world
• Have several problems related to network
• Consistent distributed information
• Guaranteeing real-time interactivity
• Contending with limited network bandwidth
• Common features of Net-VE
• Shared sense of space, presence and time
• Way to communicate and share
• Interact realistically with other users and with
  VE itself

VRE
VRE
Real-time Interaction
Sharedmemory
Sharedmemory
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IMRC Project
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Network Topology of IMRC Project
Real-time Transmission Object Information Update
Signal
VRE Biennale
VRE K-JIST
Shared memory
LoadAdaptor
Shared memory
LoadAdaptor
database
Update
Update
Visitors sculpture data For safety storing
information
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Virtual Reality Software-1

• VR-Juggler Open Source VR application
  development framework
• Interactive immersive application independently
  of the underlying technologies
• Base Application Object Interface
• init() called by kernel to initialize any
  application data
• Application setup its data structure.
• preFrame() called when the system is about to
  trigger drawing
• Reserved for last-millisecond data update from
  device input
• intraFrame() excutes in parallel with rendering
  method
• Performing computation for the next frame
• postFrame() invoked after rendering has
  completed but before updates devices and other
  internal data
• Synchronizing with external networking

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VR-Juggler Kernel Loop Sequence
vjKernel
vjGlApp
vjGlDraw Manager
vjinput Manager
Init()
InitAPI()
apiInit()
VRE
while
preFrame()
draw()
intraFrame()
sync()
Network
postFrame()
Send Data
updateAllData()
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Virtual Reality Software-2

• CAVELib API that provides the cornerstone for
  creating robust interactive I3D environment
• CAVELib Callbacks
• Display graphics routine to be rendered (called
  times per frame)
• Passing this function pointer to CAVEDisplay()
• Frame update called exactly once per frame in
  each rendering thread
• Passing this function pointer to
  CAVEFrameFunction()
• Initialization called exactly once prior to
  CAVEInit()
• Passing this function pointer to
  CAVEInitApplication()
• Data Synchronization
• CAVEMasterDisplay() returns true in exactly one
  display thread/process
• CAVEDisplayBarrier() the display
  threads/processes to block until all of them have
  called it

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CAVELib Program Flow
CAVEinit()
Create thread for each display pipe
Init application callback function
Init application callback function
Main process User responsible for This process
Farame update callback function
Farame update callback function
while
Graphics callback function
Graphics callback function
Barrier wait for all display process to finish
rendering all data
Swap buffer
Swap buffer
Update variables (Master thread)
Barrier wait for master process to finish
updating shared data
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Coupling VR-Juggler and CAVELib

• The biggest difference with VR-juggler and
  CAVELib
• VR-Juggler doesnt have to manage shared memory
  with other VR Juggler instances. Thus, memory can
  be created as in normal C
• Requirement for coupling is common data structure
• Common network interface and data formation are
  needed for object transfer
• Use some parts of Quanta library
• In general, data formation for object information

Object ID position (x,y,z) additional
information
Predictive data or Synchronization data
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The Existing Problems in NVE

• VR software has similar architecture to handle
  shared data in processes or thread. But they
  focus only on synchronization between local
  processes
• Additional factors for networked virtual
  environments to be consistent
• Different delay
• Different jitter
• Different rendering or processing power
• Although network bandwidth problem is solved,
  these factors still remain for distributed
  virtual environment
• If we consider these factors, it would be needed
  to provide other VREs with information like
  timestamp
• when you should draw this graphic data
• Limitation of waiting for other VREs to avoid
  deadlock
• These information can be used to calculate
  several delays, so it makes adaptive
  synchronization delay possible

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Future work

• IMRC Project
• Support the integration of immersive components
  by Feb.
• Practice VR-Juggler and Quanta library
• Writing network game program which is simple but
  scalable and stable by using VR-juggler and
  Quanta
• Recognize practical problems in Net-VE
• Enhance the performance of the game with adapting
  several algorithm