Indexing and Retrieval of Satellite Images Thesis for the Degree of Master of Science in Computer Science and Engineering

INDEXING AND RETRIEVAL OF SATELLITE IMAGES by Aiyesha L. Ma Adviser: Ishwar K. Sethi, Ph.D. As sensors and hardware advance, vast amounts of data are being collected, yet much of this data is stored and not analyzed for useful information. In the area of weather imagery, part of the reason is because retrieval is based on information not related to the content contained in the image. By allowing retrieval of historical data, meteorologists may gain insight to the current weather patterns. With this motivation, this thesis presents a shape-based retrieval system and its application to infrared satellite images. A complete system is presented, from region extraction of a full hemisphere scan to the actual retrieval mechanism. From full hemisphere scans of the earth, regions are extracted using region growing. After region extraction, polygonal approximation is applied to the region shape, and local features of the polygons are hashed to provide an association space. This space becomes the indexing structure through which retrieval takes place. Although the indexing stage, containing region extraction and polygonal approximation, is slow, the actual retrieval is very fast. On average, retrieval of a query shape from a database of 1965 shapes takes 0.7 seconds for the more reduced representation, and 2.8 seconds for the less reduced representation consisting of 1914 shapes.