This is an example using more advanced tools than the examples .... and .... Image pre_processing and merging of mutiple fields.
Open the example UVMAT_DEMO_FILES/EX07_convection . 

= calibration =
mark corners

= mask =

= sub_background =

= first PIV =

= making two masks =
The parietal jet requires a very good resolution, particularly among x. To limitate PIV to this jet, let us create a specific mask.
Open the previously created contour polygon contour_mask.xml in uvmat  by the menu bar '''!Tools/Projection object/browse...'''. Check the box '''edit''' (tag '''[!CheckEditObject]''') in the frame '''Object''' of uvmat (right hand side) to allow editing of the polygon. then replace the lower x bound 0 by 52. Then create the corresponding mask by '''Tools/make mask''', save it with name Dalsa1.mask/mask_plume.png. Similarly create a mask for the bulk Dalsa1.mask/mask_bulk.png, with bounds in x [0 55].
  
= PIV on the parietal plume =
Choose the following parameters:
 * pair j=1-2 for Civ1 and Civ2 : it minimises the time interval which is needed to capture the large velocity in the plume.
 * !CorrBox x,y=(5 31) which optimizes the resolution in x (5 pixels)
 * Search x, y=(25 55) which allows for a larger velocity component along y .
 * auto-grid Dx=2, Dy=10, consistent with !CoorBox (about half the box size).
 * Mask selected, with name .../Dalsa1.mask/mask_plume.png .
 * For Civ2, same parameters !CorrBox, auto-grid and Mask.
 * For patch and Fix, default parameters.

= PIV on the interior =
Select the pair j=1-3 to deal with the small velocities (considering that the parietal plume has been masked). Then use the default parameters.

= merging data on a common grid = 
create a projection grid in phys coordinates. For that open a velocity field with uvmat, displayed in phys coordinates. Use the upper bar menu option Projection object/plane. Then in the GUI '''set_object''', choose the option !ProjMode=interp_lin. Choose a mesh 0.2 cm in each direction, ranging from 0 to 55 in x and 0 to 58.8 in y. Press REFRESH to see the result of projection in the GUI view_field. Check the option '''nb_vec/4''' to reduce the number of vectors displayed on the plot.
Now in series open the PIV file Dalsa1.sback.civ_bulk as input. Then append the second file Dalsa1.sback.civ_plume using the menu bar selection '''Open/Browse append...'''.