Location-based data visualization employing geographical information system and information visualization provides an advanced means to assist with visual data exploration, hypothesis formation and decision making. An effective location-based data visualization system can significantly enhance the communication among decision-makers and facilitate the agreement on the most appropriate alternatives. This study presents SmartGIS, a tool integrating SVG, Web GIS, and data visualization techniques to augment the analytical capabilities of GIS-based spatial and temporal decision-making process. It provides an intuitive, interactive manipulation of SVG-based SARS map, dynamically generated from GIS database. SmartGIS provides hierarchical operations to allow a user to view SARS data at multiple levels of details on the Web. This facilitates the continuously visualizing and monitoring of SARS outbreak status. The implementation issues of SmartGIS are described and its applications to other areas are discussed.