Abstract

This thesis, Earth satellites and detection of air- and ground-based activities by Ulf Ekblad of the Physics department at the Royal Institute of Technology (KTH), addresses the problem of detecting military activities in imagery. Examples of various techniques are presented. In particular, problems associated with "novelties" and "changes" in an image are discussed and various algorithms presented. The imagery used includes satellite imagery, aircraft imagery, and photos of flying aircraft. The timely delivery of satellite imagery is limited by the laws of celestial mechanics. This and other information aspects of imagery are treated. It is e.g. shown that dozens of satellites may be needed if daily observations of a specific site on Earth are to be conducted from low Earth orbit. New findings from bioinformatics and studies of small mammal visual systems are used. The Intersecting Cortical Model (ICM), which is a reduced variant of the Pulse-Coupled Neural Network (PCNN), is used on various problems among which are change detection. Still much more could be learnt from biological systems with respect to pre- and post-processing as well as intermediate processing stages. Simulated satellite imagery is used for determining the resolution limit for detection of tanks. The necessary pixel size is shown to be around 6 m under the conditions of this simulation. Difference techniques are also tested on Landsat satellite imagery with the purpose of detecting underground nuclear explosions. In particular, it is shown that this can easily be done with 30 m resolution images, at least in the case studied. Satellite imagery from SPOT is used for detecting underground nuclear explosions prior to the detonations, i.e. under certain conditions 10 m resolution images can be used to detect preparations of underground nuclear explosions. This type of information is important for ensuring the compliance of nuclear test ban treaties. Furthermore, the necessity for having complementary information in order to be able to interpret images is also shown.

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