Sviquel: a Spatial Visual Query and Exploration Language Sviquel: a Spatial Visual Query and Exploration Language

The need to analyze and query spatial data is becoming increasingly important with the advent of applications such as Geographic Information Systems, Image Databases and Remote Sensing. The focus of our research is to support spatial data analysis by developing a direct manipulation environment to visually query as well as browse spatial data and to review the visual results for trend analysis. In this paper, we present a visual query language (SVIQUEL) which allows us to specify the relative spatial position (both topology and direction) between objects using direct manipulation. This query language builds upon the notion of dynamic query lters and signiicantly extends them to support integrated querying of both topological and directional types of spatial data. In order to facilitate continuous querying as required by a direct manipulation environment, we designed an integrated neighborhood model for both kinds of spatial relationships (topology and direction). Our spatial query palette SVIQUEL allows us to query over any of the continuous sets of neighboring values. SVIQUEL is complimented by a Spatial Query Disambiguation diagram (SQUAD) which gives qualitative visual representations of the quantitative query. This increases the utility of the system for spatial browsing of data with no particular query in mind. Mapping functions between the quantitative SVIQUEL and the qualitative SQUAD have been developed. The resulting tight coupling between SVIQUEL and SQUAD allows the users to work with either qualitative query speciications or at a quantitative level of detail depending on his particular needs as well as to freely switch between the two while working in a continuous data exploration mode.