On Scene Flow Computation of Gas Structures with Optical Gas Imaging Cameras

Gas leak inspection and gas leak quantification are nowadays of high relevance within the oil and gas industry as well as in many other industrial sectors. This has been driven by safety-related issues, economic losses and the considerable climate impact caused by such unwanted gas releases. Due to the latter, the efforts for developing new and more reliable measurement techniques for detecting and quantifying greenhouse gases such as methane have increased in the recent years. In this work, a stereo camera system based on optical gas imaging cameras is used for computing dense 3D velocity information, i.e. scene flow, of escaping gas structures. Here, the optical flow, the disparity and the disparity change in likely gas image regions are computed utilizing classical variational methods. The accuracy of the applied methods and their applicability under real conditions in a biogas plant are characterized and tested. The results show that the recovered 3D gas velocity field per camera frame approaches the average 3D velocity field of the measured gas structure. The accuracy of the used method is affected, among others, when the imaged gas structures exhibit a low contrast.