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Fourier Transform Techniques for Imaging Performance Evaluations of Thermal Imaging Cameras Used by the Fire Service.

pdf icon Fourier Transform Techniques for Imaging Performance Evaluations of Thermal Imaging Cameras Used by the Fire Service. (155 K)
Amon, F. K.; Ducharme, A.

Volume 2;

Interflam 2007. (Interflam '07). International Interflam Conference, 11th Proceedings. Volume 2. September 3-5, 2007, London, England, 1537-1542 pp, 2007.


fire departments; fire investigations; FT-IR; thermal imaging; evaluation; fire fighting; methodology; fire fighters; first responders


Infrared (IR) technology for fire fighting applications has matured to the point that most first responder organizations in the U. S. either have purchased or are considering the purchase of thermal imaging cameras. Thermal imagers can provide first responders with critical information to size up a fire incident, track fire growth, and to locate victims, other first responders, and egress routes. While these devices represent a significant investment, typically on the order of $10 K per camera, first responders have little guidance on instrument performance beyond manufacturer literature and recommendations from other users. These issues are further complicated because the demands placed on thermal imagers are application dependent. The end users may have very different ideas about which imaging properties are most important: sharp image contrast may be sufficient for some fire fighting applications, such as finding the source of a fire, but high thermal sensitivity may be required to locate a person or structural component when flames and water are in the imager's field of view. Currently, there are no standardized performance guidelines available to aid end users in making purchasing decisions. Over the past several years, the Fire Research Division at the National Institute of Standards and Technology has been developing a suite of performance metrics and test methods for inclusion in a national consensus-based standard on thermal imaging cameras used by first responders. The performance metrics are related directly to the environment in which the imagers are used and taskstypically performed by first responders. Measurements of contrast, effective temperature range, spatial resolution, image uniformity, thermal sensitivity, and the ability to penetrate obscuring media such as smoke and water vapor are currently included in the draft standard. The test methods associated with two of these performance metrics, e.g., spatial resolution and effective temperature range, may benefit from a careful analysis of the frequency content of the images that appear on the imager's display screen. As a subset of the overall project, NIST is working with the College of Optics and Photonics at the University of Central Florida to investigate two techniques for transferring the essential characteristics of complex images generally seen in the fire environment to relatively simple bench top target configurations for use in standardized performance tests.