Distributed Image Search in Sensor Networks

Recent advances in sensor networks permit the use of a large number of relatively inexpensive distributed computa- tional nodes with camera sensors linked in a network and possibly linked to one or more central servers. We argue that the full potential of such a distributed system can be realized if it is designed as a distributed search engine where images from different sensors can be captured, stored, searched and queried. However, unlike traditional image search engines that are focused on resource-rich situations, the resource lim- itations of camera sensor networks in terms of energy, band- width, computational power, and memory capacity present significant challenges. In this paper, we describe the de- sign and implementation of a distributed search system over a camera sensor network where each node is a search engine that senses, stores and searches information. Our work in- volves innovation at many levels including local storage, lo- cal search, and distributed search, all of which are designed to be efficient under the resource constraints of sensor net- works. We present an implementation of the search engine on a network of iMote2 sensor nodes equipped with low- power cameras and extended flash storage. We evaluate our system for a dataset comprising book images, and demon- strate more than two orders of magnitude reduction in the amount of data communicated and upto 5x reduction in over- all energy consumption over alternate techniques.