3-D Reconstruction of Gas Clouds by Scanning Imaging IR Spectroscopy and Tomography

In the case of accidents at chemical plants, during transportation of chemicals, or after terrorist attacks, hazardous compounds may be released into the atmosphere. The weather-dependent propagation of these toxic clouds can threaten population and environment. In order to apply appropriate safety measures, it is necessary for emergency response forces to detect and identify the regarding substances. In addition, it is important to determine position, dimensions, and source of the gas cloud. Moreover, it is desirable to perform the necessary measurements from a distance to minimize the threat for emergency response personnel. Imaging remote sensing by IR spectroscopy provides a method for generating (2-D) images of the cloud. Combined with an appropriate visible (video) or IR image of the scene, these images can reveal information like the dimensions and the location of the source of the cloud. Nevertheless, the distance between the system and the cloud and the dimensions of the cloud along the line of sight are not available if a single image is measured. If images of the cloud are recorded from at least two different positions at the same time, information about the position and the 3-D shape of the cloud becomes available. Therefore, a method for 3-D reconstruction of gas clouds based on imaging IR spectroscopy and tomography has been developed. The remote sensing system, the measurement setup, and the algorithm generating the 3-D structures from the images are described. The method is applied to reconstruct the exhaust gas plume of an industrial stack.