Dynamic view-dependent multiresolution on a client-server architecture

We consider the problem of transmitting huge triangle meshes in the context of a Web-like client-server architecture. Approximations of the original m esh are transmitted by applying selective refinement. A multiresolution geo metric model is maintained by the server. A client may query the server for a mesh at an arbitrary, continuously variable, level of detail. The client makes repeated queries over time with different query parameters. The serv er answers to queries by traversing the multiresolution model and transmitt ing updates to the client, which uses them to progressively modify a curren t mesh. We study this problem in the context of a vertex-based multiresolution mode l, which is a special instance of the Multi-Triangulation (a model that was developed in an earlier work), based on vertex insertion and removal. We d efine a compact data structure for such a model that exploits the specific update rule. We propose a dynamic algorithm for selective refinement and we discuss in detail its implementation as a client-server application. In or der to reduce memory requirements and channel traffic, we develop a compres sed representation which allows us to express mesh updates with a code of s mall size. We also address client caching to further limit bandwidth occupa ncy. Experimental results show that the Multi-Triangulation can be a key We b technology for triangle mesh manipulation. (C) 2000 Elsevier Science Ltd. All rights reserved.