Changes between Version 11 and Version 12 of Tutorial/ParticleImageVelocimetry


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Timestamp:
Dec 10, 2014, 12:01:37 AM (6 years ago)
Author:
sommeria
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  • Tutorial/ParticleImageVelocimetry

    v11 v12  
    3333
    3434== Histograms ==
    35 The global histograms of the vector components  are available in the lower left windows. Histograms limited to a sub-region can be extracted by the menu bar tool '''[Projection object]''', selecting either ['''rectangle]''', '''[ellipse]''' or '''[polygon]''' to define the sub-region (see [wiki:"Tutorial: projection objects" Tutorial: projection objects])
     35The global histograms of the vector components  are available in the lower left windows. Histograms limited to a sub-region can be extracted by the menu bar tool '''[Projection object]''', selecting either ['''rectangle]''', '''[ellipse]''' or '''[polygon]''' to define the sub-region (see [wiki:Tutorial/ProjectionObjects: projection objects])
    3636
    3737== Profiles ==
     
    5858
    5959The time interval between the two images, Dt=0.02 s, must be introduced in this xml file by adding a section <Camera>, using a text editor:
    60 <ImaDoc>
     60<!ImaDoc>
    6161  <Camera>
    62            <TimeUnit>s</TimeUnit>
     62           <!TimeUnit>s</TimeUnit>
    6363           <BurstTiming>
    6464                   <Dti>0.02</Dti>
    65                    <NbDti>1</NbDti>
     65                   <!NbDti>1</NbDti>
    6666           </BurstTiming>
    6767  </Camera>
     
    9191This can be avoided by using a mask, which is an image of the same size as the images used for PIV. Grey color in the mask indicate regions excluded from measurement.
    9292
    93 To produce the mask, first create a polygon by the menu bar command [Projection object/mask polygon]. Draw the mask with the mouse by moving around regions to exclude. Left mouse button to initiate the plot and produce new boundary points, press right hand button to finalise the polygon. By default mask is set inside the polygon, but it can be made outside by selecting the option ’mask_outside’ in the menu [ProjMode] of the GUI set_object.
     93To produce the mask, first create a polygon by the menu bar command [Projection object/mask polygon]. Draw the mask with the mouse by moving around regions to exclude. Left mouse button to initiate the plot and produce new boundary points, press right hand button to finalise the polygon. By default mask is set inside the polygon, but it can be made outside by selecting the option ’mask_outside’ in the menu [!ProjMode] of the GUI set_object.
    9494
    95 Then 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’).
     95Then 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’).
    9696
    9797The 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, the mask is introduced by the selecting the green check box [Mask]. Vectors under the mask are not calculated in the resulting velocity data.
     
    126126The following figure shows the final vorticity field, in which the vorticity roll up in the wake of the sphere is clearly visible. A zoom near a vortex shows the vorticity superposed with velocity vectors.
    127127
    128 [[Image(vort_civ3.jpg)]]
     128[[Image(vort_civ3-2.jpg)]]
    129129[[Image(vort_vel_zoom.jpg)]]
    130130