An SVG-based method to support spatial analysis in XML/GML/SVG-based WebGIS

XML/GML/SVG based approaches are promising for building Web-based geographic information system (WebGIS). However, current XML/GML/SVG based WebGISs are lacking in spatial analysis. Some of them are designed for web mapping only. Others adopt a server-side solution for spatial analysis, which suffers from the “bottleneck” problem, and results in a high network transmission load. Load balancing spatial analysis between server side and browser side can be used to solve the above problems. This paper focuses on one of the key building blocks of load balancing spatial analysis, i.e., SVG-based spatial analysis which enables spatial querying and analysis directly on SVG (on the browser side). After analyzing the workflow of spatial analysis, we identify and focus on two key issues in providing spatial analysis on SVG: SVG-based spatial information representation and SVG-based Spatial Extended SQL (SSESQL). For the first issue, a theoretical foundation is set up to develop an SVG-based spatial information representation model. Some spatial operators are designed and integrated into an SSESQL to support spatial querying on SVG. Finally we design and implement two case studies. The results of these case studies show that the proposed method is feasible and operable in supporting spatial analysis directly on SVG on the browser side. The proposed method can be easily incorporated with some existing methods (e.g., GML-based spatial analysis on the server side) to provide load balancing spatial analysis (load balancing between server side and browser side) in XML/GML/SVG based WebGIS. As a result, users can access high performance spatial analysis simply via a web browser (such as, Internet Explorer and Firefox). 2