Tomographic reconstruction and efficient rendering of refractive gas flows


This chapter introduces techniques for the capture and efficient display of dynamic three-dimensional non-stationary gas flows. We describe a flexible Schlieren-tomographic system consisting of multiple consumer camcorders. A special choice of background pattern for Background Oriented Schlieren (BOS) imaging provides for flexibility in the experimental setup. Optical flow techniques are used to measure image space deflections due to heated air flows from arbitrary camera positions. A specially tailored sparse-view algebraic reconstruction algorithm is employed to tomographically recover a refractive index gradient field. After robust integration of these gradient fields, time-varying, fully three-dimensional refractive index fields are obtained. These can be rendered efficiently using a ray-casting style algorithm that is suitable for graphics hardware acceleration. Additional optical properties can be rendered within the same computational framework.

Imaging Measurement Methods for Flow Analysis