Changes between Version 18 and Version 19 of Tutorial/ParticleImageVelocimetry

Timestamp:

Jan 15, 2015, 4:14:28 PM (9 years ago)

Author:

vaillant1p

Comment:

--

Tutorial/ParticleImageVelocimetry

@@ -93 +93 @@
 This 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.
 
-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.
+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'''.
 
-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’).
+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’).
 
-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, the mask is introduced by the selecting the green check box [Mask]. Vectors under the mask are not calculated in the resulting velocity data.
+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''', the mask is introduced by the selecting the green check box '''[Mask]'''. Vectors under the mask are not calculated in the resulting velocity data.
 
 = Refined PIV =
 
-To improve the results, come back to the GUI CIV , and follow these successive steps, corresponding to a sequence of operations.
+To improve the results, come back to the GUI '''CIV''', and follow these successive steps, corresponding to a sequence of operations.
 Optimizing the Civ1 parameters
 
-Select the [CIV1] check box so the corresponding parameters show up. Improve the spatial resolution by selecting smaller correlation boxes in the civ1 menu, for instance [Bx],[By] to 19 and 13 (image pixels). This is possible because of the good image quality and high particle density. The use of a smaller box in y allows to optimize the resolution in this direction, to deal with the strong vertical shear. It is now possible to adjust the search range, using knowledge on extremal velocities, see histograms displayed by uvmat in phys coordinates. We introduce estimated bounds on each velocity component, [min] to -2 and [max] to 6 for ’u’ and (-3, 3) for ’v’, and press the button [Search Range] . The optimum search ranges and shifts are now displayed. In consistency with higher resolution, we set the grid mesh to [Dx] and [Dy] to 10. Finally select the Mask option : the mask name should be displayed in the corresponding edit box, else a browser leads to the appropriate mask file.
+Select the '''[CIV1]''' check box so the corresponding parameters show up. Improve the spatial resolution by selecting smaller correlation boxes in the '''civ1''' menu, for instance [Bx],[By] to 19 and 13 (image pixels). This is possible because of the good image quality and high particle density. The use of a smaller box in y allows to optimize the resolution in this direction, to deal with the strong vertical shear. It is now possible to adjust the search range, using knowledge on extremal velocities, see histograms displayed by '''uvmat''' in phys coordinates. We introduce estimated bounds on each velocity component, [min] to -2 and [max] to 6 for ’u’ and (-3, 3) for ’v’, and press the button '''[Search Range]'''. The optimum search ranges and shifts are now displayed. In consistency with higher resolution, we set the grid mesh to [Dx] and [Dy] to 10. Finally select the '''Mask option''' : the mask name should be displayed in the corresponding edit box, else a browser leads to the appropriate mask file.
 FIX1