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Proceedings Paper

Perceptual evaluation of visual alerts in surveillance videos
Author(s): Bernice E. Rogowitz; Mercan Topkara; William Pfeiffer; Arun Hampapur
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Paper Abstract

Visual alerts are commonly used in video monitoring and surveillance systems to mark events, presumably making them more salient to human observers. Surprisingly, the effectiveness of computer-generated alerts in improving human performance has not been widely studied. To address this gap, we have developed a tool for simulating different alert parameters in a realistic visual monitoring situation, and have measured human detection performance under conditions that emulated different set-points in a surveillance algorithm. In the High-Sensitivity condition, the simulated alerts identified 100% of the events with many false alarms. In the Lower-Sensitivity condition, the simulated alerts correctly identified 70% of the targets, with fewer false alarms. In the control condition, no simulated alerts were provided. To explore the effects of learning, subjects performed these tasks in three sessions, on separate days, in a counterbalanced, within subject design. We explore these results within the context of cognitive models of human attention and learning. We found that human observers were more likely to respond to events when marked by a visual alert. Learning played a major role in the two alert conditions. In the first session, observers generated almost twice as many False Alarms as in the No-Alert condition, as the observers responded pre-attentively to the computer-generated false alarms. However, this rate dropped equally dramatically in later sessions, as observers learned to discount the false cues. Highest observer Precision, Hits/(Hits + False Alarms), was achieved in the High Sensitivity condition, but only after training. The successful evaluation of surveillance systems depends on understanding human attention and performance.

Paper Details

Date Published: 17 March 2015
PDF: 13 pages
Proc. SPIE 9394, Human Vision and Electronic Imaging XX, 939413 (17 March 2015); doi: 10.1117/12.2085802
Show Author Affiliations
Bernice E. Rogowitz, Visual Perspectives Research and Consulting (United States)
Mercan Topkara, JW Player (United States)
William Pfeiffer, Microsoft Corp. (United States)
Arun Hampapur, IBM Thomas J. Watson Research Ctr. (United States)

Published in SPIE Proceedings Vol. 9394:
Human Vision and Electronic Imaging XX
Bernice E. Rogowitz; Thrasyvoulos N. Pappas; Huib de Ridder, Editor(s)

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