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An imaging sensor simulation model is described which allows a modeled or measured scene radiance map to be displayed on a video monitor as it would be seen if viewed through a simulated sensor under simulated environmental conditions. The model includes atmospheric effects (transmittance, path radiance, and single-scattered solar radiance) by incorporating a modified version of the LOWTRAN 6 code. Obscuration and scattered radiance introduced into the scene by battlefield induced contaminants are represented by a battlefield effects module. This module treats smoke clouds as a series of Gaussian puffs whose transport and diffusion are modeled in a semi-random fashion to simulate atmospheric turbulence. The imaging sensor is modeled by rigorous application of appropriate optical transfer functions with appropriate insertion of random system noise. The simulation includes atmospheric turbulence transfer functions according to the method of Fried. Of particular use to sensor designers, the various effects may be applied individually or in sequence to observe which effects are responsible for image distortion. Sensor parameters may be modified interactively, or recalled from a sensor library. The range of the sensor from a measured scene may be varied in the simulation, and background and target radiance maps may be combined into a single image. The computer model itself is written in FORTRAN IV so that it may be transported between a wide variety of computer installations. Currently, versions of the model are running on a VAX 11/750 and an Amdahl 5860. The model is menu driven allowing for convenient operation. The model has been designed to output processed images to a COMTAL image processing system for observer interpretation. Preliminary validation of the simulation using unbiased observer interpretation of minimum resolvable temperature (MRT)-type bar patterns is presented.
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