面向P2P网络的渐进式三维场景更新策略

近年来网上大规模虚拟环境实时漫游已经成为WebGIS的新兴研究领域。为缓解用户终端极其有限的存储空间与海量场景之间的矛盾，设计了一种面向对等网的新型渐进式场景更新策略(PSRM)。在剔除场景前，节点通过分别计算场景文件对自身视点的“视觉保留度”、场景文件对自身兴趣区域(AOI)邻居的“潜在贡献度”及“物体重用度”，综合确定需要被剔除的场景，并按照逐渐降低场景分辨率的策略剔除旧有场景数据。仿真显示，PSRM在下载饱满度、基网格下载饱满度两个衡量漫游效果的重要指标上较现有系统有明显提升,同时能大幅降低漫游过程中的服务器端负载。

Progressive 3D scenes replacement mechanism for P2P overlay

Recently, walkthrough system of large-scale virtual environments has been a new topic of WebGIS. In order to relieve the contradiction between limit storage of user terminal and massive 3D scenes via Internet, the authors proposed a new Progressive Scenes Replacement Mechanism (PSRM) which suited the Peer-to-Peer (P2P) overlay. New concepts of "reuse degree", "visual preservation", and "preservation for Area of Interest (AOI) neighbors" were introduced respectively. Thus, the old scenes which needed to be replaced could be identified, and these scenes were replaced from high resolution to low resolution progressively. The simulation results show the PSRM improves more in the downloading fill ratio, downloading fill ratio of base mesh compared with the current system, and the workload of server is reduced greatly by using PSRM in the walkthrough.