SEVA

Abstract

In this article, we study how a sensor-rich world can be exploited by digital recording devices such as cameras and camcorders to improve a user's ability to search through a large repository of image and video files. We design and implement a digital recording system that records identities and locations of objects (as advertised by their sensors) along with visual images (as recorded by a camera). The process, which we refer to as Sensor-Enhanced Video Annotation (SEVA) , combines a series of correlation, interpolation, and extrapolation techniques. It produces a tagged stream that later can be used to efficiently search for videos or frames containing particular objects or people. We present detailed experiments with a prototype of our system using both stationary and mobile objects as well as GPS and ultrasound. Our experiments show that: (i) SEVA has zero error rates for static objects, except very close to the boundary of the viewable area; (ii) for moving objects or a moving camera, SEVA only misses objects leaving or entering the viewable area by 1--2 frames; (iii) SEVA can scale to 10 fast-moving objects using current sensor technology; and (iv) SEVA runs online using relatively inexpensive hardware.