Implementation of Progressive Transmission Algorithms for Vector Map Data in Web-based Visualization

This paper investigates the benefits of progressive transmission of vector data, through designing and developing a hierarchical data model to compress vector data for progressive transmission over the internet. The aim of the hierarchical data model is to extract a coarse vector data set using vertex removal operations. Furthermore, a set of rules are proposed to control the validity of topology for the ‘coarse’ vector data version, and a recovery algorithm is developed to reconstruct the ‘finer’ vector data on the client side. The proposed method reconstructs the original data. The overall procedure is to (a) extract coarser data version on the server side on-line; (b) transmit coarser data version to the client; and (c) progressively recover more detailed data on the client side. An experimental prototype system has been developed to test the performance of the proposed method and illustrate its strengths and weaknesses. The experimental results show that the method can efficiently simplify spatial data, can maintain the shapes characteristics of objects during transmission, and improves transmission time over internet greatly.