近年來，網路頻寬、電腦計算能力及電腦繪圖技術的長足進步，使得網路虛擬環境（Networked Virtual Environments, NVEs）呈現蓬勃的發展。提高擴充性(scalability)是網路虛擬環境的一個重要議題。本計畫預計採用zone-based multi-server 架構，將整個虛擬世界切割為許多大小固定的六角形區域，讓每個伺服器根據其容量(capacity)可以管理數量不同的連續區域(其中管理相鄰區域的伺服器稱為相鄰伺服器)。我們預計達成以下三個目標： 1. 伺服器間動態負載分擔：我們藉由負載圖(load graph)描述伺服器間的負載關係，過載的(overloaded)伺服器依據其相鄰伺服器的現況，動態地將其負載分散給相鄰的低載(underloaded)伺服器，使其負載低於均負載臨界值(evenload threshold)，以達到伺服器間動態負載分擔的功能。 2. 無縫區域間使用者互動：相鄰伺服器會相互複製其邊界區域的事件以支援使用者跨區互動，並藉以建立低延遲的用戶跨區換手(handoff)機制。 3. 虛擬環境一致性控制：伺服器藉由精確同步的時鐘值(timer)將所有接收到的事件訊息加上時機戳記，配合本地延遲(local lag)、死算(dead reckoning)及回溯(rollback)技術，在達到NVE的高反應性(responsiveness)的同時，並確保虛擬環境物件狀態的一致性。 ; A networked virtual environment (NVE), also known as the distributed virtual environment (DVE) or the collaborative virtual environment (CVE), is a computer-generated virtual world where multiple users can assume virtual representatives (or avatars) to concurrently interact with each other via networked links. Recently, there is a trend that NVEs are apt to have an increasing number of users. Therefore, how to increase the scalability is an important problem in NVEs. In the project, we propose using zone-based multi-server architecture to partition the virtual world into fixed-sized hexagonal zones such that servers can manage different numbers of contiguous zones according to their capacity. (If two servers manage neighboring zones, they are called neighboring servers and the zones are called boundary zones.) We plan to achieve the following three goals in the project. 1. Dynamic load sharing among servers: We describe the load relationship of servers by the load graph, by which overloaded server can distribute part of its load to neighboring underloaded servers to achieve the goal. 2. Seamless interaction between zones: In every NVE step, each server copies the events happening within the boundary zones to the associated neighboring servers to achieve seamless inter-zone interaction and to cut down the handoff cost when users are crossing the border of neighboring boundary zones. 3. Networked virtual environment consistency control: Severs are assumed to have accurate synchronized timers and will attach a timestamp to each received event message. By the techniques of local lag, dead-reckoning and rollback, we intend to achieve high responsiveness while keeping consistent the states of the networked virtual environment. ; 研究期間 9808 ~ 9907
