Changes between Version 12 and Version 13 of Tutorial/AdvancedParticleImagingVelocimetry
- Timestamp:
- Jan 15, 2015, 4:31:00 PM (9 years ago)
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Tutorial/AdvancedParticleImagingVelocimetry
v12 v13 14 14 == Global PIV == 15 15 == PIV in two subregions == 16 The PIV computation is launched from the GUI ''''civ' ''' opened from uvmat by the upper bar command '''[RUN/PIV/CIV]'''. This GUI can be also directly opened by typing 'civ' in the Matlab command window, and the input image file then opened by the upper bar command '''[ Open/Browse]''', like in the GUI uvmat. The name CIV means Correlation Imaging Velocity to stress that the method relies on image correlations, which detect the displacement of image textures, not necessarily from particles.16 The PIV computation is launched from the GUI ''''civ' ''' opened from uvmat by the upper bar command '''[RUN/PIV/CIV]'''. This GUI can be also directly opened by typing 'civ' in the Matlab command window, and the input image file then opened by the upper bar command '''[!Open/Browse]''', like in the GUI uvmat. The name CIV means Correlation Imaging Velocity to stress that the method relies on image correlations, which detect the displacement of image textures, not necessarily from particles. 17 17 18 18 The PIV operation depends on many parameters, but the default values proposed by the GUI provide a good first approach in many cases. Press '''[RUN] ''' to get the result. The button is then colored in grey until the computation is finished. The operation produces a file with format netcdf, extension '''.nc''', in a subdirectory called ''''CIV' ''' by default. The file name ends with index string '_1-2' indicating that it results from images 1 and 2. The file name and its status is indicated in a new figure '''civ_status'''. Press the file name to open it with uvmat, or use the browser of '''uvmat'''. … … 21 21 22 22 == Visualizing the velocity fields == 23 } '''{** Vectors'''} To read the velocity field, open it with the GUI ''''uvmat''''. Velocity vectors are displayed in the central window, while the histograms of each component are in the lower left windows, see Fig. [uvmat_fig]. The arrow length is automatically set by default. It can be adjusted by the edit box '''[ VecScale]''' in the frame '''[Vectors']''' on the right hand side.23 } '''{** Vectors'''} To read the velocity field, open it with the GUI ''''uvmat''''. Velocity vectors are displayed in the central window, while the histograms of each component are in the lower left windows, see Fig. [uvmat_fig]. The arrow length is automatically set by default. It can be adjusted by the edit box '''[!VecScale]''' in the frame '''[Vectors']''' on the right hand side. 24 24 25 The vector color indicates the quality of the image correlation maximum leading to each vector, blue is excellent, green average, red poor. The thresholds for such color display can be adjusted from 0 to 1 (perfect image correlation) in the frame''' [Vectors]''', using the boxes '''[ ColCode1] ''' and '''[ColCode2]''', or equivalently by the corresponding sliders '''[Slider1]''' and '''[Slider2] '''.25 The vector color indicates the quality of the image correlation maximum leading to each vector, blue is excellent, green average, red poor. The thresholds for such color display can be adjusted from 0 to 1 (perfect image correlation) in the frame''' [Vectors]''', using the boxes '''[!ColCode1] ''' and '''[!ColCode2]''', or equivalently by the corresponding sliders '''[Slider1]''' and '''[Slider2] '''. 26 26 27 Vector color can also represent another quantity, as chosen in the menu '''[ ColorScalar] ''' in the frame '''[Vectors]'''. For instance the vector length norm_vec can be used. Then a color continuous 64 color code is appropriate, as set in the menu '''[ColorCode]'''. The color codes values between the valuies set by '''[MinVec] ''' and '''[MaxVec].'''27 Vector color can also represent another quantity, as chosen in the menu '''[!ColorScalar] ''' in the frame '''[Vectors]'''. For instance the vector length norm_vec can be used. Then a color continuous 64 color code is appropriate, as set in the menu '''[!ColorCode]'''. The color codes values between the valuies set by '''[!MinVec] ''' and '''[!MaxVec].''' 28 28 29 29 The position (x,y) and velocity components (U,V) can be displayed in the upper right text display window by moving the mouse over it.
