Research Of Progressive Streaming Transmission Of Vector Spatial Data In Web Map

The progressive streaming transmission of spatial vector data provides Internet users with a self-adaptive strategy to access remote data. The transmission is achieved by gradually adding details from low resolution to high resolution. The transmission not only speeds up the data transfer but also offers an efficient navigation guide in information acquisition. The progressive transmission of raster images via the Internet has become commonplace. But the progressive transmission of vector geospatial data remains a challenge.This thesis aims at vector data offering a new multiple representation model called changes accumulation model, which considers the spatial representation from one scale to another scale as an accumulation of set of changes. The difference between two consecutive representations is recorded in a linear index and through gradually addition or subtraction realizes the progressive streaming transmission.This thesis presents design and implementation of a method that progressively transmits vector data of polyline and rivers network. The key technology of the method is the efficient multiple representation of vector data and pre-organization on server site by changes accumulation model. The thesis develops an architecture including multi-scale spatial database, server and client.