Integration of Qualitative Spatial Reasoning into GIS- An Example with SparQ

Jan Sahib, Chipofya Malumbo

Abstract

Qualitative Spatial Reasoning (QSR) is a subfield of knowledge representation and symbolic reasoning that deals with knowledge about usually infinite spatial domains using a finite set of qualitative relations. Qualitative knowledge is a relative knowledge where we obtain the knowledge on the basis of comparisons of spatial features within the object domain rather than using some external scale. Spatial reasoning is present in our everyday interaction with the geographical world and qualitative spatial knowledge is ubiquitous in the realms human spatial reasoning. In particular, we use orientation information and approximate distances to locate places in space. This point, among others, motivates the integration of QSR into Geographic Information Systems (GIS). During the last two decades a multitude of formal calculi over spatial relations has been proposed focusing on different aspects of space like topology, orientation, and distance. However, the application of these calculi in GIS remains sparse. One reason for this is the lack of appropriate implementations and corresponding user interaction models. We approach this problem by building an appropriate Application Programming Interface (API) that encapsulates the functionalities of the qualitative spatial reasoner SparQ to make them available to GIS applications. This is the first step towards a more generic model that can allow multiple reasoners to be accessed in a single workflow of a GIS and for qualitative spatial reasoning tasks to be chained with limited intervention from the user. Our API which is written in Java provides a set of Extensible Markup Language (XML) data structure for specifying the query to SparQ and returning the results. The API itself resides on the client-side and accepts XML structured queries which it then passes on to SparQ in the latter's own syntax. Results from SparQ are converted back into XML and returned to the user application. In this paper we will first describe the API we developed for SparQ and how it has been tested with the open source java-based GIS software OpenJUMP. Then we will note some shortcomings of our work especially with respect to the applicability of the API in a broader context, for example SparQ and therefore our API does not support polygon (geometry) type entities which are common in geospatial datasets. Finally, we will discuss some future directions for our work and the challenges we envisage.

Projects the publication originates from