Journal ArticleDOI
Fluid flow and optical flow
Tianshu Liu,Lixin Shen +1 more
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TLDR
The connection between fluid flow and optical flow is explored in typical flow visualizations to provide a rational foundation for application of the optical flow method to image-based fluid velocity measurements as discussed by the authors.Abstract:
The connection between fluid flow and optical flow is explored in typical flow visualizations to provide a rational foundation for application of the optical flow method to image-based fluid velocity measurements. The projected-motion equations are derived, and the physics-based optical flow equation is given. In general, the optical flow is proportional to the path-averaged velocity of fluid or particles weighted with a relevant field quantity. The variational formulation and the corresponding Euler–Lagrange equation are given for optical flow computation. An error analysis for optical flow computation is provided, which is quantitatively examined by simulations on synthetic grid images. Direct comparisons between the optical flow method and the correlation-based method are made in simulations on synthetic particle images and experiments in a strongly excited turbulent jet.read more
Citations
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Journal ArticleDOI
Optical flow modeling and computation
TL;DR: A survey of optical flow estimation classifying the main principles elaborated during this evolution, with a particular concern given to recent developments is proposed.
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Variational fluid flow measurements from image sequences: synopsis and perspectives
TL;DR: This work outlines promising research directions and points out the potential of variational techniques in combination with correlation-based PIV methods, for improving the consistency of fluid flow estimation and simulation.
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Risk assessment of airborne transmission of COVID-19 by asymptomatic individuals under different practical settings
Siyao Shao,Dezhi Zhou,Ruichen He,Jiaqi Li,Shufan Zou,Kevin Mallery,Santosh Kumar,Suo Yang,Jiarong Hong +8 more
TL;DR: In this article, the authors quantify the exhaled particles from normal respiratory behaviors and their transport under elevator, small classroom, and supermarket settings to evaluate the risk of inhaling potentially virus-containing particles.
Journal ArticleDOI
Dense motion estimation of particle images via a convolutional neural network
TL;DR: Experimental evaluations indicate that the trained CNN model can provide satisfactory results in both artificial and laboratory PIV images, and the computational efficiency of the CNN estimator is much superior to those of the traditional cross-correction and optical flow methods.
Journal ArticleDOI
Particle Image Velocimetry Based on a Deep Learning Motion Estimator
TL;DR: Experimental results indicate that the proposed estimator can provide accuracy approaching that of state-of-the-art methods and high efficiency toward real-time estimation.
References
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Journal ArticleDOI
Determining optical flow
TL;DR: In this paper, a method for finding the optical flow pattern is presented which assumes that the apparent velocity of the brightness pattern varies smoothly almost everywhere in the image, and an iterative implementation is shown which successfully computes the Optical Flow for a number of synthetic image sequences.
Proceedings ArticleDOI
Determining Optical Flow
TL;DR: In this article, a method for finding the optical flow pattern is presented which assumes that the apparent velocity of the brightness pattern varies smoothly almost everywhere in the image, and an iterative implementation is shown which successfully computes the Optical Flow for a number of synthetic image sequences.
Journal ArticleDOI
A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses
TL;DR: In this paper, a two-stage technique for 3D camera calibration using TV cameras and lenses is described, aimed at efficient computation of camera external position and orientation relative to object reference coordinate system as well as the effective focal length, radial lens distortion, and image scanning parameters.
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A versatile camera calibration technique for high-accuracy 3D machine vision metrology using off-the-shelf TV cameras and lenses
TL;DR: A new technique for three-dimensional camera calibration for machine vision metrology using off-the-shelf TV cameras and lenses using two-stage technique has advantage in terms of accuracy, speed, and versatility over existing state of the art.