Improving Accessibility of Web-Based GIS Applications

A major problem of vector active map formats such as WebCGM and scalable vector graphics (SVG) is that, in order to display them in most Web browsers, either a plug-in has to be installed or an applet has to be downloaded. In this paper, a Web service is presented whose functionality enables the transformation of vector active maps from SVG to a new DHTML (HTML+JavaScript) active map representation, improving this way the accessibility of Web-based GIS applications. This new representation, which is also part of the present work, includes a raster representation of the map and a vector representation of its geographic objects. The former is used as a background image of the map whereas the latter enables the response to user-triggered events. An R-tree spatial index structure is used to access the geographic objects affected by each event in order to execute the relevant action