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 =