FireMapperTM: A Thermal-Imaging Radiometer for Wildfire Research and Operations

U.S. Government work not protected by U.S. copyright. IEEE AC paper #1522. Abstract— Airborne trials have produced the first applications of a new thermal-imaging radiometer, the FireMapper, which is a unique three-channel, calibrated imaging system designed through a Research Joint Venture between the USDA Forest Service and Space Instruments, Inc. FireMapper has been designed to map the progress and intensity of wildland fires but has sufficient sensitivity to be useful in terrain mapping, disaster management, and naturalresource monitoring. FireMapper employs a microbolometer detector array that requires no cryogenic cooling, as do conventional mercury-cadmium-telluride detectors, and thus offers a less complex and less expensive thermal-imaging system. The prototype design employs a filter wheel to provide two narrow-band channels, at wavelengths of 8.1 to 9 μm and 11.4 to 12.4 μm, and a broadband channel from 8.1 to 12.4 μm. Calibrations of radiance as a function of instrument digital number are stable and highly linear. The 11.4to 12.4-μm channel, which saturates only above 1216° C, has proven useful in characterizing the very high radiances associated with major flaming fronts. Two levels of onboard blackbody calibration provide real-time correction of offset drift in the detector array and an absolute through-the-lens blackbody calibration upon user demand. The latter corrects for reflections within the instrument and produces a flat-field image of the target scene. Digital time-delay integration may also be selected to improve measurement sensitivity. The onboard user interface provides real-time image viewing and enhancement, instrument setup and control, and real-time data on instrument status. Results show that the FireMapper can successfully characterize flaming front environments and temperatures with the potential for improving tactical fire suppression operations, fire-fighter safety, and our understanding of fire behavior and the environmental impacts of wildland fire. TABLE OF CONTENTS