关键词: 大规模虚拟场景，渐进式传输，潜在可视场景集，分布式虚拟环境，场景预下载

Abstract: With the rapid enlargement of 3D virtual scenes on Internet, the contradiction between the requirement of fast downloading from user and limited bandwidth is more seriously. Now many researchers have been working on fast downloading of large scale virtual scenes form Internet by progressive transmission strategy, so it is necessary to give an overview of existed works. This paper introduced the principle and main processes of progressive transmission with a formula to evaluate different transmission strategies firstly, then described the progressive transmission strategy of downloading large scale virtual scenes from: (1) the determination of PVS(Potential Visible Scenes) and the Incremental PVS, (2) the predigestion techniques and streaming encoding of 3D o均ect model, (3) the transmission mechanisms of virtual scenes in different DVE (Distributed Virtual Environment),(4) the polices of prefetching virtual scenes. The technical prospect on progressive transmission of large scale virtual scenes on Internet is given at last.

Key words: Large scale virtual scenes, Progressive transmission, PVS, DVE, Scene prefetching