Changes between Version 1 and Version 2 of Tutorial/ParticleImageVelocimetry


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Timestamp:
Aug 26, 2013, 11:09:23 PM (11 years ago)
Author:
sommeria
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  • Tutorial/ParticleImageVelocimetry

    v1 v2  
     1Open again the first example EX1_pair.
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    13== Visual check ==
    2  Particle Image Velocimetry (PIV) measures the displacement of features in a pair of images, and  a visual evidence of feature displacement between the two images is a prerequisite  for success of the computation. To observe this motion, write the file indices 1 and 2 in the boxes '''[i1]''' and '''[i2]''' respectively, in the frame '''[File Indices]''' on the left. Then push the red button '''[<html><--></html>]''' in the frame '''[Navigate]''', see figure. The image then alternatively switches from 1 to 2. The speed of motion can be adjusted with the slider '''[speed]'''. Press '''[STOP]''' to stop the motion.
     4Particle Image Velocimetry (PIV) measures the displacement of features in a pair of images. Visual evidence of feature displacement between the two images is a prerequisite  for the success of the computation. To observe this motion, write the file indices 1 and 2 in the boxes '''[i1]''' and '''[i2]''' respectively, in the frame '''[File Indices]''' on the left. Then push the red button '''[<html><--></html>]''' in the frame '''[Navigate]''', see figure. The image then alternatively switches from 1 to 2. The speed of motion can be adjusted with the slider '''[speed]'''. Press '''[STOP]''' to stop the motion.
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    46<doc138|center>
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    68== Launching PIV ==
    7  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.
     9The PIV computation is launched from the GUI 'civ', opened from uvmat by the upper bar command '''[RUN/PIV]''', or from '''series''' by selecting the function '''civ_series'''. 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.
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    911The 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'''.