VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD

An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm) submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with...

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Main Authors: Johan Debayle, Ahmed Raihane, Abdelkrim Belhaoua, Olivier Bonnefoy, Gérard Thomas, Jean-Marc Chaix, Jean-Charles Pinoli
Format: Article
Language:English
Published: Slovenian Society for Stereology and Quantitative Image Analysis 2011-05-01
Series:Image Analysis and Stereology
Subjects:
Online Access:http://www.ias-iss.org/ojs/IAS/article/view/847
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spelling doaj-0fb6cca135c140a0ad28b18d94f8a2262020-11-25T00:00:49ZengSlovenian Society for Stereology and Quantitative Image AnalysisImage Analysis and Stereology1580-31391854-51652011-05-01281354310.5566/ias.v28.p35-43819VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHODJohan DebayleAhmed RaihaneAbdelkrim BelhaouaOlivier BonnefoyGérard ThomasJean-Marc ChaixJean-Charles PinoliAn image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm) submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.http://www.ias-iss.org/ojs/IAS/article/view/847grain motiongranular mediahorizontal vibrationsmultiscale image analysisoptical flowvelocity field
collection DOAJ
language English
format Article
sources DOAJ
author Johan Debayle
Ahmed Raihane
Abdelkrim Belhaoua
Olivier Bonnefoy
Gérard Thomas
Jean-Marc Chaix
Jean-Charles Pinoli
spellingShingle Johan Debayle
Ahmed Raihane
Abdelkrim Belhaoua
Olivier Bonnefoy
Gérard Thomas
Jean-Marc Chaix
Jean-Charles Pinoli
VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
Image Analysis and Stereology
grain motion
granular media
horizontal vibrations
multiscale image analysis
optical flow
velocity field
author_facet Johan Debayle
Ahmed Raihane
Abdelkrim Belhaoua
Olivier Bonnefoy
Gérard Thomas
Jean-Marc Chaix
Jean-Charles Pinoli
author_sort Johan Debayle
title VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
title_short VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
title_full VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
title_fullStr VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
title_full_unstemmed VELOCITY FIELD COMPUTATION IN VIBRATED GRANULAR MEDIA USING AN OPTICAL FLOW BASED MULTISCALE IMAGE ANALYSIS METHOD
title_sort velocity field computation in vibrated granular media using an optical flow based multiscale image analysis method
publisher Slovenian Society for Stereology and Quantitative Image Analysis
series Image Analysis and Stereology
issn 1580-3139
1854-5165
publishDate 2011-05-01
description An image analysis method has been developed in order to compute the velocity field of a granular medium (sand grains, mean diameter 600 μm) submitted to different kinds of mechanical stresses. The differential method based on optical flow conservation consists in describing a dense motion field with vectors associated to each pixel. A multiscale, coarse-to-fine, analytical approach through tailor sized windows yields the best compromise between accuracy and robustness of the results, while enabling an acceptable computation time. The corresponding algorithmis presented and its validation discussed through different tests. The results of the validation tests of the proposed approach show that the method is satisfactory when attributing specific values to parameters in association with the size of the image analysis window. An application in the case of vibrated sand has been studied. An instrumented laboratory device provides sinusoidal vibrations and enables external optical observations of sand motion in 3D transparent boxes. At 50 Hz, by increasing the relative acceleration G, the onset and development of two convective rolls can be observed. An ultra fast camera records the grain avalanches, and several pairs of images are analysed by the proposed method. The vertical velocity profiles are deduced and allow to precisely quantify the dimensions of the fluidized region as a function of G.
topic grain motion
granular media
horizontal vibrations
multiscale image analysis
optical flow
velocity field
url http://www.ias-iss.org/ojs/IAS/article/view/847
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