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A sophisticated and flexible digital infrared data collection system has been assembled at the Georgia Tech Research Institute. The system includes such components as two radiometers responding in the 3 -5 and 8 -12 micron spectral bands, a near infrared television, and a master computer which performs the data acquisition and permanent storage function. In addition, a second computer system is included allowing for off -line image analysis. The application software development and hardware interfacing comprised the majority of the effort described herein. The purpose of the system is to allow for the collection of infrared target signature data which hopefully will enhance development of phenomenological and semi-empirical thermal models. This paper presents a description of the instrumentation hardware and software as well as details on the interface between sensors, computers, and additional peripherals. The details of a recent system characterization activity are also included. System description SensorsThe infrared sensors selected for the data collection system are two Inframetrics 600 thermal imaging systems operating in the 3 -5 micron and 8 -12 micron regions. A Hamamatsu silicon CID TV unit is used to collect near infrared imagery in the nominal 0.7 to 0.9 micron spectral band.The Inframetrics model 600 radiometer is a new product similar to the model 525 but with several features making it especially useful in a remote data collection system. The

Experiments were conducted to determine the influence of background clutter on target detection criteria. The experiment consisted of placing observers in front of displayed images on a TV monitor. Observer ability to detect military targets embedded in simulated natural and manmade background clutter was measured when there was unlimited viewing time.Results were described in terms of detection probability versus target resolution for various signal to clutter ratios (SCR). The experiments were preceded by a search for a meaningful clutter definition. The selected definition was a statistical measure computed by averaging the standard deviation of contiguous scene cells over the whole scene. The cell size was comparable to the target size. Observer test results confirmed the expectation that the resolution required for a given detection probability was a continuum function of the clutter level. At the lower SCRs the resolution required for a high probability of detection was near 6 lines pairs per target (LP /TGT), while at the higher SCRs it was found that a resolution of less than 0.25 LP /TGT would yield a high probability of detection. These results are expected to aid in target acquisition performance modeling and to lead to improved specifications for imaging automatic target screeners.Background

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