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1、2005/06/22,NCSLAB,1,結合即時控制系統架構之3D介面VR 系統分析,電機系控制組(D92921003)黃雋博(R93921067)彭詩淵,2005/06/22,NCSLAB,2,Outline,MotivationSystem ArchitectureTechniqueA case studyConclusion,2005/06/22,NCSLAB,3,Motivation,Interactive game environmentreal time system which can interact with other peopleKeeping the system ma
2、intain the display rate with 25 frame/s.,2005/06/22,NCSLAB,4,Motivation,In the on-line interactive VR system,the delay will be occurred in many situations.Therefore,the timing analysis is very important for this project.The delay events that we predict are as bellow:Delay in server:Calculation time(
3、modeling,numerical)Separate the whole environment for individual clientDelay in network time:Conjunction delayCompensationDelay in client:Rendering(According to hardware of the system)Request for the server,2005/06/22,NCSLAB,5,System Architecture,2005/06/22,NCSLAB,6,Technique,Control over Quality,Ba
4、ndwidth,Buffer Condition,CPUs Utilization,Scheduling Techniques for real time-systems(Ex:Rate Monotonic(RM)Algorithm,Earliest Deadline First(EDF)Algorithm),2005/06/22,NCSLAB,7,Technique,2005/06/22,NCSLAB,8,Technique,Teb:encoder buffering delayTdb:decoder buffering delayTe:encoding delayTd:decoding d
5、elayTc:networking delayTnm:numerical method computing delayTpm:physics model computing delayTv:visualization delayTeb+Tdb+Te+Td+Tc+Tnm+Tpm+Tv40ms,2005/06/22,NCSLAB,9,Technique,Level of Details(LOD)techniqueLOD rendering techniques reduce the geometric complexity of 3D models,sacrificing visual rende
6、ring quality in order to increase frame rendering rates.,Physically-based:based on physical lows or mathematical functions-complex but realNon physically-based game:do not use physical laws-simple but unrealTry the best to reduce the high computational costs and maintain the reality,2005/06/22,NCSLA
7、B,10,A case study,Non-physical based methodGrassland by Neyret 1998translates texture to show the animated grassland,Neyret 1998,LOD example-Grassland Perbet and Cani 2001,highest LOD model,middle LOD model,lowest LOD model,2005/06/22,NCSLAB,11,Physical based models,Cantilever beam model Anjyo et al
8、.1992,Mass spring damped model Miller 1988,Mass-spring modelProvot 1995,A case study,2005/06/22,NCSLAB,12,A case study,Set spring between the massesAssume the position of i th particle is the position of i+1 th particle is the internal force between the i th spring is Each particle has gravity,wind
9、resistance and buoyancy,Use Eulers method,2005/06/22,NCSLAB,13,A case study,1000-Grass ENVIRONMENT,2005/06/22,NCSLAB,14,For(i=0;iGrassNum;i+)IF(ViewerPOS.Z-grassi.Z)HighLODRange)grassiHighLODVisualization Else grassiLowLODVisualization,X,Y,Z,2005/06/22,NCSLAB,15,A Case Study,For Client/Sever,1000-Gr
10、ass ENVIRONMENT,733MHZ Pentium III CPU,3GHZ Pentium IV CPU,2005/06/22,NCSLAB,16,Scheduling,2005/06/22,NCSLAB,17,Scheduling,EDF,2005/06/22,NCSLAB,18,Experiment,Particle:6240 vs.14040,2005/06/22,NCSLAB,19,Experiment-Low Quality,2005/06/22,NCSLAB,20,Experiment-High Quality,2005/06/22,NCSLAB,21,Experime
11、nt-Optimal,2005/06/22,NCSLAB,22,Conclusion,The concept of LOD is used to maintain the human impression under real-time requirement.The timing analysis for real-time has been established.the rate control for large number of the VR scenario have been discussed.,2005/06/22,NCSLAB,23,References,Neyret 1
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16、X.Zhuang,“Rate-distortion model based rate control for real-time VBR video coding and low-delay communications,”Signal Processing:Image Communication.Vol.17,No.2,pp.187-199,2002.D.Wu et al.2000 D.Wu,Y.T.Hou,and Y.Q.Zhang,“Transporting Real-Time Video over the Internet:Challenges and Approaches,”Proc
17、eedings of the IEEE,Vol.88,Issue 12,pp.1855-1877,2000.B.Li and K.Nahrstedt 1999 B.Li and K.Nahrstedt,“A control-based middleware framework for quality-of-service adaptations,”IEEE Journal on Selected Areas in Communications,Vol.17,Issue 9,pp.1632-1650,1999.C.Lu et al.2002 C.Lu,J.A.Stankovic,G.Tao,an
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