Chinese Journal of Computers   Full Text
Title	A Method Based on the Degree of Object Attributes Attention for Transmission QoS Control
Authors	XIE Ke LIANG Xiao-Hui ZHAO Qin-Ping
Address	(State Key Laboratory of Virtual Reality Technology and Systems, School of Computer Science and Engineering, Beihang University, Beijing 100191)
Year	2009
Issue	No.1(115—123)
Abstract &   Background	Abstract In Distributed Virtual Environment, it is an important issue that how to manage the distribution of 3D geometry. Instead of downloading the whole virtual world objects into the clients’ machines, on-demand method is to copy only objects that the user needs - partial replication of a virtual world rather than full replication. Therefore, a key aspect is how to efficiently replicate the required data in real-time. To solve this problem, a QoS transmission control method and a QoS Management Model, which are based on the degree of object attributes attention, are given in this paper. This method extends the traditional geometry-based model transmission control method. Non-geometric attributes and geometric attributes are integrated together and regarded as QoS parameters. Because real-time property is the most important requirements in distributed virtual environment and it can be affected by network bandwidth during the run time, a dynamic negotiation algorithm, which combines the idea of dynamic QoS management, is given in this paper. Experimental results show that the method is able to reflect user’s level of concern about virtual objects in virtual environment comprehensively, and it can gain better transmission results while ensuring the prerequisite of real-time with the changing of the network bandwidth. Keywords distributed virtual environment; geometry resource; real-time; virtual object attributes; dynamic QoS management Background This work is supported by the National Natural Science Foundation of China under grant No.60873159, Program for New Century Excellent Talents in University (NCET), National High Technology Research and Development Program (863 Program) of China under grant No.2006AA01Z333 and Graduate Innovative Practice Fund Project of Beihang University. In DVR design, a central problem is geometry data replication. At present, there are two strategies to deal with this problem. The first one is geometric resources pre-distributed. For supporting real-time interaction, it is common to replicate the whole virtual world data at the client, and in the runtime only update the message of states to maintain the consistency of application. But as the scale of the virtual world is enlarged, the transmission overhead increases even more significantly, especially when replicating the data from the server to each client. The second one is on-demand transmission techniques. Instead of downloading the whole virtual world objects into clients’ machines, only objects that the user needs are copied—Partial replication of a virtual world rather than full replication. Therefore, a key aspect is how to efficiently replicate the required data in real time. Most related works are based on the information of avatar’s geometric attributes, such as the spatial relationship between the avatar and other objects (e.g. distance). To solve this problem, this paper proposes a method based on the degree of object attributes attention for transmission QoS control in DVR. This method extends the traditional geometry-based model of information transmission control methods. Non-geometric attributes and geometric attributes are integrated together and regarded as QoS parameters. In the processing of DVR system, this method gives a dynamic negotiation algorithm which combines the idea of dynamic QoS management. The results presented in this work are able to comprehensive reflect user’s level of concern about virtual object in virtual environment, and it can gain better transmission results while ensuring the prerequisite of real-time with the changing of the network bandwidth.