Wavelet-Based Optical Flow Analysis for Background-Oriented Schlieren Image Processing

A wavelet-based optical flow analysis (wOFA) method for processing background-oriented schlieren (BOS) images is presented and demonstrated on synthetic experimental data. Optical inherently well suited to BOS, because the background pattern lighting conditions are specified controlled by user can be chosen play strengths of processing. Analysis BOS data show that a two-dimensional sinusoidal produces highest reconstruction accuracy both wOFA iterative least squares (ILS) algorithms. outperforms ILS in terms overall displacement fields with sufficiently high spatial frequency content. In addition, provides higher resolution, about an order magnitude total number pixels final image. Finally, two sets data: heat gun plume experiment nearly ideal imaging characteristics, experiments supersonic wind tunnel more realistic restrictions acquisition images. computed shown have resolution sensitivity than ILS, without introducing additional noise. Therefore, able reveal features not detected analysis.