Date: Tuesday January 15 2002
Time: 10.30 - 11.30
Place: Aula G3b Padiglione G Via Opera Pia 15 GENOVA

Speaker: Prof. Hanan Samet
Department of Computer Science
University of Maryland
Title: Pictorial Query Specification for Browsing Through Spatially-Referenced Image Databases (Joint work with Aya Soffer)

Abstract. A pictorial query specification technique that enables the formulation of complex pictorial queries for browsing through a collection of spatially-referenced images is presented. It is distinguished from most other methods by the fact that in these methods the query image specifies a target database image in its entirety whereas in our approach the query image specifies the combination of objects that the target database image should contain rather than being treated as a whole image. Using our technique, it is possible to specify which particular objects should appear in the target images, how many occurrences of each object are required, and spatial constraints that specify bounds on the distance between objects and the relative direction between them. Each pictorial query is composed of one or more query images. Each query image is constructed by selecting the required query objects and positioning them according to the desired spatial configuration. Boolean combinations of two or more query images are also possible by use of AND and OR operators. A query image may be negated in order to specify conditions that should not be satisfied by the database images that are retrieved successfully. In addition, a capability is provided to specify whether the same instance of an object is to be used when it appears in more than one of the query images that make up the pictorial query, or whether two different instances are allowed. Several example queries are given that demonstrate the expressive power of this query specification method in an application that browses the results in a map image database application.