Changes between Version 49 and Version 50 of Tutorial/ParticleImageVelocimetry


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Timestamp:
Mar 24, 2015, 10:53:51 AM (6 years ago)
Author:
vaillant1p
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  • Tutorial/ParticleImageVelocimetry

    v49 v50  
    1212The PIV computation is accessed from '''uvmat''' by the upper bar command '''[Run/PIV]''', or from '''series''' by selecting the function '''civ_series'''. The name 'CIV' means '''C'''orrelation '''I'''maging '''V'''elocity to stress that the method relies on image correlation, which evaluates the displacement of image textures, not necessarily from particles. Note that an older GUI ''''civ' '''is also available, but it is obsolete and not used here.
    1313
    14 A new GUI '''civ_input''' now appears. In the menu '''[!ListCompareMode]''', keep the default option 'PIV'. Keep the default option 'Di=0|1' for the image pair (menu tag '''[!ListPairCiv1]''') and the default parameters in the frame '''CIV1'''. Press '''[OK]''' so the GUI '''civ_input''' desappears.  Then press '''[RUN] ''' in the GUI''' series''' to run the calculation. The button '''[RUN]''' is then colored to yellow until the computation is finished.
     14A new GUI '''civ_input''' now appears. In the menu '''[!ListCompareMode]''', keep the default option 'PIV'. Keep the default option 'Di=0|1' for the image pair (menu tag '''[!ListPairCiv1]''') and the default parameters in the frame '''CIV1'''. Press '''[OK]''' so the GUI '''civ_input''' desappears.  Then change '''i_last''' to 2 and press '''[RUN] ''' in the GUI''' series''' to run the calculation. The button '''[RUN]''' is then colored to yellow until the computation is finished.
    1515
    1616The operation produces a  file with format netcdf, named with extension '.nc', in a folder called 'Images.civ'. This can be viewed by pressing '''[STATUS] '''in the GUI '''series''', which displays the result file 'frame_1-2.nc'. The index string '_1-2' indicates that it results from images 1 and 2. Select the file name and press '''[OPEN]''' to open it directly with '''uvmat''', or use the browser of '''uvmat'''.
     
    8989Then the mask itself is produced by the menu bar command '''[!Tools/Make mask]'''. The corresponding image is then displayed and stored by default in the directory of the initial image. Note that if several mask polygons have been initially created, as listed in '''[!ListObject]''' (bottom right of the GUI uvmat), they will be merged as dark regions in the resulting mask (useful in case of multiple ’holes’).
    9090
    91 The mask image can be seen as a mask by selecting '''[view_mask]''' at the upper left of the GUI '''uvmat'''. For checking purpose, it can be also opened by the browser of '''uvmat''' like any image. In the GUI '''civ_input''', the mask is introduced by the selecting the green check box '''[Mask]'''. Vectors under the mask are not calculated in the resulting velocity data.
     91The mask image can be seen as a mask by selecting '''[view_mask]''' at the upper left of the GUI '''uvmat''' next to '''[REFRESH]'''. For checking purpose, it can be also opened by the browser of '''uvmat''' like any image. In the GUI '''civ_input''', the mask is introduced by the selecting the green check box '''[Mask]'''. Vectors under the mask are not calculated in the resulting velocity data.
    9292
    9393[[Image(Tutorial5 - CIV with mask.png)]]