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 '''edit''' (tag '''[!CheckEditObject]''').
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 =

= PIV on the interior =

= merging data on a common grid =