Sketch-based image queries in topographic databases

In this paper we present the development of a system prototype for sketch-based queries for the content-based retrieval of digital images from topographic databases. We discuss our overall strategy and associated algorithmic and implementation aspects, and we present associated database design issues. The query tools devised in this research are employing user-provided sketches of the shape and spatial configuration of the object(s) which should appear in the images to be retrieved. Our matching tool is inspired by least-squares matching (Ism) and represents an extension of Ism to function with a variety of raster representations. Our strategy makes use of a hierarchical organization of feature shapes within a feature library. The results are ranked according to statistical scores and the user can subsequently narrow or broaden his/her search according to the previously obtained results and the purpose of the search. Our approach combines the design of an integrated database environment with the development of a feature library and the necessary matching tools. We discuss our overall strategy and individual database components and present some implementation results. (C) 1999 Academic Press.