关键词: WebGIS, 大规模虚拟环境, 对等网, 保留度, 渐进式场景更新

Abstract: 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.

Key words: WebGIS, large-scale virtual environments, Peer-to-Peer (P2P), preservation degree, Progressive Scenes Replacement Mechanism (PSRM)