Changes between Version 29 and Version 30 of Tutorial/ParticleImageVelocimetry


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Timestamp:
Jan 21, 2015, 2:18:41 PM (6 years ago)
Author:
vaillant1p
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  • Tutorial/ParticleImageVelocimetry

    v29 v30  
    6969</ImaDoc>
    7070}}}
    71 Then open the image with uvmat. The label 'xml' should appear in the upper right box [[!TimeName]] and time value beside it in [[!TimeValue]].
     71Then open the image with uvmat. The label 'xml' should appear in the upper right box '''[!TimeName]''' and time value beside it in '''[!TimeValue]'''.
    7272
    7373Now repeat the PIV operation to include the time information in the result (in the absence of time information the file index is taken as default value).
     
    8686The parameters '''[num_Dx]''' and '''[num_Dy] '''define the mesh of the measurement grid, in pixels. Reduce them to get more vectors, but keep in mind that the spatial resolution is limited by the size of the correlation box.
    8787
    88 The PIV operation is conveniently visualised by pressing the button '''[!TestCiv1]''' in the GUI civ. Then the image appear in a new GUI '''view_field''', in which the mouse motion displays the correlation function, which appears in a secondary window, see figure. The resulting vector is shown as a line pointing to the correlation maximum. The corresponding correlation and search boxes are shown in the image. Let us run again PIV with [!CorrBoxSize]=[25 25] and [!SearchBoxSize]=[33,33], limiting ourselves to CIV1, and visualisae the result with '''uvmat'''. Many black vectors (F=-2) are obtained, showing that the search domain is too small, so that the correlation maximum is constrained by the limited search interval. Repeat the operation with ! [https://servforge.legi.grenoble-inp.fr/projects/soft-uvmat/search?q=wiki%3ASearchBoxSize SearchBoxSize]=[35,33], then the arrows are not black anymore.
     88The PIV operation is conveniently visualised by pressing the button '''[!TestCiv1]''' in the GUI civ. Then the image appear in a new GUI '''view_field''', in which the mouse motion displays the correlation function, which appears in a secondary window, see figure. The resulting vector is shown as a line pointing to the correlation maximum. The corresponding correlation and search boxes are shown in the image. Let us run again PIV with [!CorrBoxSize]=[25 25] and [!SearchBoxSize]=[33,33], limiting ourselves to CIV1, and visualisae the result with '''uvmat'''. Many black vectors (F=-2) are obtained, showing that the search domain is too small, so that the correlation maximum is constrained by the limited search interval. Repeat the operation with [https://servforge.legi.grenoble-inp.fr/projects/soft-uvmat/search?q=wiki%3ASearchBoxSize SearchBoxSize]=[35,33], then the arrows are not black anymore.
    8989
    9090= Masks =
     
    116116The status of the calculation is displayed in a new window which refreshes automatically. Close it to avoid blocking of new Matlab operations. This status window can be opened again by pushing the button '''[STATUS]''' in the GUI '''civ'''. Do not close civ until the calculation is finished.
    117117
    118 The parameters of a CIV computation are stored in a xml file with extension ..[wiki:CivDoc].xml created in the directory containing the velocity files. These parameters can retrieved, opening this xml file with the browser of the GUI '''civ'''. Then the image file itself needs to be opened (the select again the check boxes for the operations beyond civ1 hidden by default).
     118The parameters of a CIV computation are stored in a xml file with extension ..!CivDoc.xml created in the directory containing the velocity files. These parameters can retrieved, opening this xml file with the browser of the GUI '''civ'''. Then the image file itself needs to be opened (the select again the check boxes for the operations beyond civ1 hidden by default).
    119119
    120120The result can be improved again by performing a third civ iteration, civ3. For that purpose, select only the ’'''civ2'''’, ’'''fix2'''’ and ’'''patch2'''’ operations with the same parameters as previously. The previous result is now considered as ’'''civ1'''’, so set CIV as the subdirectory in the edit window '''[SubDirCiv1]'''. Select a new subdirectory name, for instance ’CIV3’ in the edit window '''[SubDirCiv2]'''. Further iterations could be similarly performed, but the improvement becomes negligible.