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The background-oriented Schlieren technique has emerged as a promising method for visualizing density gradients and performing quantitative measurements. However, an inherent constraint of BOS is the compromise between spatial resolution…

Fluid Dynamics · Physics 2025-09-08 Xiang Li , Muen Gao , Weiran Wang , Jiawei Li , Chong Pan , Jinjun Wang , Yuan Xiong

We propose a dot-tracking methodology for processing Background Oriented Schlieren (BOS) images. The method significantly improves the accuracy, precision and spatial resolution compared to conventional cross-correlation algorithms. Our…

Fluid Dynamics · Physics 2019-10-23 Lalit K. Rajendran , Sally P. M. Bane , Pavlos P. Vlachos

Non-intrusive quantitative fluid density measurements methods are essential in stratified flow experiments. Digital imaging leads to synthetic Schlieren methods in which the variations of the index of refraction are reconstructed…

Fluid Dynamics · Physics 2015-11-11 Lilly Verso , Alex Liberzon

Particle Image Velocimetry (PIV) is a widely adopted non-invasive imaging technique that tracks the motion of tracer particles across image sequences to capture the velocity distribution of fluid flows. It is commonly employed to analyze…

Computer Vision and Pattern Recognition · Computer Science 2026-01-05 Yunzhong Zhang , Bo Xiong , You Zhou , Changqing Su , Zhen Cheng , Zhaofei Yu , Xun Cao , Tiejun Huang

An important tool for experimental fluids mechanics research is Particle Image Velocimetry (PIV). Several robust methodologies have been proposed to perform the estimation of velocity field from the images, however, alternative methods are…

Computer Vision and Pattern Recognition · Computer Science 2025-02-03 Efraín Magaña , Francisco Sahli Costabal , Wernher Brevis

We build an ultra-high-speed imaging system based on the background-oriented schlieren (BOS) technique in order to capture a laser-induced underwater shock wave. This BOS technique is able to provide two-dimensional density-gradient field…

Fluid Dynamics · Physics 2015-03-20 Shota Yamamoto , Yoshiyuki Tagawa , Masaharu Kameda

Particle Imaging Velocimetry (PIV) estimates the flow of fluid by analyzing the motion of injected particles. The problem is challenging as the particles lie at different depths but have similar appearance and tracking a large number of…

Computer Vision and Pattern Recognition · Computer Science 2020-03-24 Zhong Li , Jinwei Ye , Yu Ji , Hao Sheng , Jingyi Yu

Particle Image Velocimetry (PIV) is a method of im-aging and analysing fields of flows. The PIV tech-niques compute and display all the motion vectors of the field in a resulting image. Speeds more than thou-sand vectors per second can be…

Hardware Architecture · Computer Science 2008-07-24 Alain Aubert , Nathalie Bochard , Virginie Fresse

Diffractive optical element based background oriented schlieren (BOS) is a popular technique for quantitative flow visualization. This technique relies on encoding spatial density variations of the test medium in the form of an optical…

Image and Video Processing · Electrical Eng. & Systems 2025-10-01 Viren S. Ram , Tullio de Rubeis , Dario Ambrosini , Rajshekhar Gannavarpu

Optical images of transparent three-dimensional objects can be different from a replica of the object's cross section in the image plane due to refraction at the surface or in the body of the object. Simulations of the object's image are…

We present a Python-based renderer built on NVIDIA's OptiX ray tracing engine and the OptiX AI denoiser, designed to generate high-quality synthetic images for research in computer vision and deep learning. Our tool enables the description…

Computer Vision and Pattern Recognition · Computer Science 2021-05-31 Nathan Morrical , Jonathan Tremblay , Yunzhi Lin , Stephen Tyree , Stan Birchfield , Valerio Pascucci , Ingo Wald

We theoretically analyze the effect of density/refractive-index gradients on the measurement precision of Volumetric Particle Tracking Velocimetry (V-PTV) and Background Oriented Schlieren (BOS) experiments by deriving the Cramer-Rao lower…

Fluid Dynamics · Physics 2020-06-24 Lalit K. Rajendran , Sally P. M. Bane , Pavlos P. Vlachos

A technique is presented for producing synthetic images from numerical simulations whereby the image resolution is adapted around prominent features. In so doing, adaptive image ray-tracing (AIR) improves the efficiency of a calculation by…

Instrumentation and Methods for Astrophysics · Physics 2015-05-20 E. R. Parkin

Quantization has emerged as a promising direction for model compression. Recently, data-free quantization has been widely studied as a promising method to avoid privacy concerns, which synthesizes images as an alternative to real training…

Computer Vision and Pattern Recognition · Computer Science 2024-02-22 Jianhong Bai , Yuchen Yang , Huanpeng Chu , Hualiang Wang , Zuozhu Liu , Ruizhe Chen , Xiaoxuan He , Lianrui Mu , Chengfei Cai , Haoji Hu

Particle Image Velocimetry (PIV) is a method to visualize the flows and quantitatively map the flows. It is used to obtain the instantaneous velocity, vorticity, divergence, shear in fluids, etc. Laser Doppler velocimetry and hot wire…

Image and Video Processing · Electrical Eng. & Systems 2020-04-23 S. Anand , R. Poovitha , K. Nikhila

We present an uncertainty quantification methodology for density estimation from Background Oriented Schlieren (BOS) measurements, in order to provide local, instantaneous, a-posteriori uncertainty bounds on each density measurement in the…

Particle Image Velocimetry (PIV) is an imaging technique in experimental fluid dynamics that quantifies flow fields around bluff bodies by analyzing the displacement of neutrally buoyant tracer particles immersed in the fluid. Traditional…

Fluid Dynamics · Physics 2025-12-15 Alan Bonomi , Francesco Banelli , Antonio Terpin

Particle Image Velocimetry (PIV) is a classical flow estimation problem which is widely considered and utilised, especially as a diagnostic tool in experimental fluid dynamics and the remote sensing of environmental flows. Recently, the…

Computer Vision and Pattern Recognition · Computer Science 2020-07-30 Mingrui Zhang , Matthew D. Piggott

Unsupervised video object segmentation (VOS), also known as video salient object detection, aims to detect the most prominent object in a video at the pixel level. Recently, two-stream approaches that leverage both RGB images and optical…

Computer Vision and Pattern Recognition · Computer Science 2024-07-17 Suhwan Cho , Minhyeok Lee , Jungho Lee , Donghyeong Kim , Seunghoon Lee , Sungmin Woo , Sangyoun Lee

The background-oriented schlieren (BOS) technique with the physics-based optical flow method (OF-BOS) is developed for measuring the pressure field of a laser-induced underwater shock wave. Compared to BOS with the conventional…

Fluid Dynamics · Physics 2016-12-21 Keisuke Hayasaka , Yoshiyuki Tagawa , Tianshu Liu , Masaharu Kameda
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