[show abstract][hide abstract] ABSTRACT: A sensor constellation capable of determining the location and detailed concentration distribution of chemical warfare agent simulant clouds has been developed and demonstrated on government test ranges. The constellation is based on the use of standoff passive multispectral infrared imaging sensors to make column density measurements through the chemical cloud from two or more locations around its periphery. A computed tomography inversion method is employed to produce a 3D concentration profile of the cloud from the 2D line density measurements. We discuss the theoretical basis of the approach and present results of recent field experiments where controlled releases of chemical warfare agent simulants were simultaneously viewed by three chemical imaging sensors. Systematic investigations of the algorithm using synthetic data indicate that for complex functions, 3D reconstruction errors are less than 20% even in the case of a limited three-sensor measurement network. Field data results demonstrate the capability of the constellation to determine 3D concentration profiles that account for ~?86%? of the total known mass of material released.
[show abstract][hide abstract] ABSTRACT: The Range Test Validation System (RTVS) includes a constellation of five AIRIS-WAD standoff multispectral sensors oriented around a 1000x1000 meter truth box at a range of 2700 meters. Column density data derived from these sensors is transmitted in real-time to a command post using a wireless network. The data is used with computed tomographic methods to produce 3-D cloud concentration profiles for chemical clouds traversing the box. These concentration profiles are used to provide referee capability for the evaluation of both point and standoff sensors under test. The system has been used to monitor chemical agent simulants released explosively as well as continuously through specialized stacks. The system has been demonstrated to accurately map chemical clouds with concentrations as low as 0.5 mg/m3 at spatial and temporal resolutions of 6 meters and 3 seconds. Data products include geo-referenced cloud mass centroids and boundaries as well as total cloud mass.