Principle and applications of the background oriented schlieren (BOS) method

Richard, Hugues; Raffel, Markus

doi:10.1088/0957-0233/12/9/325

Cited by 261 publications

(123 citation statements)

References 11 publications

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“…The initial stage of our approach is most similar to a technique called Background Oriented Schlieren (BOS, a.k.a Synthetic Schlieren) [6,8,10,12,15,18]. The optical setup in Schlieren photography is replaced by optical flow calculations on a video of a fluid in front of an in-focus textured background.…”

Section: Related Workmentioning

confidence: 99%

Refraction Wiggles for Measuring Fluid Depth and Velocity from Video

Xue¹,

Rubinstein

Wadhwa³

et al. 2014

Computer Vision – ECCV 2014

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Abstract. We present principled algorithms for measuring the velocity and 3D location of refractive fluids, such as hot air or gas, from natural videos with textured backgrounds. Our main observation is that intensity variations related to movements of refractive fluid elements, as observed by one or more video cameras, are consistent over small space-time volumes. We call these intensity variations "refraction wiggles", and use them as features for tracking and stereo fusion to recover the fluid motion and depth from video sequences. We give algorithms for 1) measuring the (2D, projected) motion of refractive fluids in monocular videos, and 2) recovering the 3D position of points on the fluid from stereo cameras. Unlike pixel intensities, wiggles can be extremely subtle and cannot be known with the same level of confidence for all pixels, depending on factors such as background texture and physical properties of the fluid. We thus carefully model uncertainty in our algorithms for robust estimation of fluid motion and depth. We show results on controlled sequences, synthetic simulations, and natural videos. Different from previous approaches for measuring refractive flow, our methods operate directly on videos captured with ordinary cameras, do not require auxiliary sensors, light sources or designed backgrounds, and can correctly detect the motion and location of refractive fluids even when they are invisible to the naked eye.

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Section: Related Workmentioning

confidence: 99%

Refraction Wiggles for Measuring Fluid Depth and Velocity from Video

Xue¹,

Rubinstein

Wadhwa³

et al. 2014

Computer Vision – ECCV 2014

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“…The fundamentals of BOS technique have been outlined in references [17] and [18], and a broad assessment is given in [19]. BOS falls in the category of pattern deflection techniques, similar to grid schlieren and moiré deflectometry, as opposed to standard schlieren, which records the variations of light intensity on the recording plane.…”

Section: Principles Of Bosmentioning

confidence: 99%

Review of background oriented schlieren and development for ballistic range applications

Gojani

Kamishi

Obayashi

2013

EPJ Web of Conferences

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Abstract. Quantitative measurements of fluid flow can be achieved by flow visualization techniques, and this paper reviews and outlines background oriented schlieren, with emphasis on its performance: measurement sensitivity and uncertainty. Since the technique depends on cross-correlation, an assessment of image evaluation is also conducted. Background oriented schlieren is applied to two flows: shock reflection from a wedge in a shock tube, and natural cooling by convection. It is estimated that the technique can be applied to ballistic facilities.

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“…The qualitative observation of the vapor phase can be done thanks to the Schlieren technique, which permits the observation of the refractive index gradient. The Background Oriented Schlieren (BOS) is described in Richard et al, (2001).…”

Section: The State Of the Art In Diesel Sprays Imagingmentioning

confidence: 99%

Characterization of Diesel Spray Images Using a Shape Processing Methodology

Petit¹,

Reckers²,

Becker³

et al. 2011

Image Anal Stereol

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In Diesel engines, a key element in achieving a clean and efficient combustion process is a proper fuel-air mixing, which is a consequence of the fuel spray development and fuel-air interaction inside the engine combustion chamber. The spray structure and behavior are classically described by the length (penetration) and width (angle) of the spray plume but these parameters do not give any clue on the geometrical injection center and on the spray symmetry. The purpose of this paper is to find out original tools to characterize the Diesel spray: the virtual spray origin is the geometrical injection center, which may (or may not) coincide with the injector axis. Another interesting point is the description of the Diesel spray in terms of symmetry: the spray plume internal and external symmetry characterize the spray and the injector performance. Our approach is first to find out the virtual spray origin: after the image segmentation, the spray is coded with the Freeman code and with an original shape coding from which the moments are derived. The symmetry axes are then computed and the spray plumes are discarded (or not) for the virtual spray origin computation, which is derived from a Voronoi diagram. The last step is the internal and external spray plume symmetry characterization thanks to correlation and mathematical distances.

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Principle and applications of the background oriented schlieren (BOS) method

Cited by 261 publications

References 11 publications

Refraction Wiggles for Measuring Fluid Depth and Velocity from Video

Refraction Wiggles for Measuring Fluid Depth and Velocity from Video

Review of background oriented schlieren and development for ballistic range applications

Characterization of Diesel Spray Images Using a Shape Processing Methodology

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