Refining Atmosphere Profiles for Aerial Target Detection Models.

Robert Grimming,Ronald Driggers,Gerald Holst,Derek Burrell,Patrick Leslie,Brian Davis

doi:10.3390/s21217067

Abstract

Atmospheric path radiance in the infrared is an extremely important quantity in calculating system performance in certain infrared detection systems. For infrared search and track (IRST) system performance calculations, the path radiance competes with the target for precious detector well electrons. In addition, the radiance differential between the target and the path radiance defines the signal level that must be detected. Long-range, high-performance, offensive IRST system design depends on accurate path radiance predictions. In addition, in new applications such as drone detection where a dim unresolved target is embedded into a path radiance background, sensor design and performance are highly dependent on atmospheric path radiance. Being able to predict the performance of these systems under particular weather conditions and locations has long been an important topic. MODTRAN has been a critical tool in the analysis of systems and prediction of electro-optical system performance. The authors have used MODTRAN over many years for an average system performance using the typical “pull-down” conditions in the software. This article considers the level of refinement required for a custom MODTRAN atmosphere profile to satisfactorily model an infrared camera’s performance for a specific geographic location, date, and time. The average difference between a measured sky brightness temperature and a MODTRAN predicted value is less than 0.5 °C with sufficient atmosphere profile updates. The agreement between experimental results and MODTRAN predictions indicates the effectiveness of including updated atmospheric composition, radiosonde, and air quality data from readily available Internet sources to generate custom atmosphere profiles.

Highlights

In the infrared systems application space, detecting dim unresolved targets against the sky path radiance is critical
When using a standard or custom atmosphere profile, a date, time, and location affect the thermal emission that makes up the path radiance
The only adjustment made was in Step 1, where a default atmosphere was selected

Summary

Introduction

In the infrared systems application space, detecting dim unresolved targets against the sky path radiance is critical. This task encompasses both military and commercial systems such as long-range aircraft detection in a passive mode (offensive infrared search and track (IRST), as well as an increasingly important function of short- and long-range drone detection. Detection with infrared cameras provides potential advantages because of a drone’s low radar signatures and use during low-light scenarios. Due to their size, these targets may be a few pixels or even unresolved at a kilometer away. A drone is detected when there is sufficient contrast with the background, in this case, the sky

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