Changes between Version 9 and Version 10 of Tutorial/CorrelationImageVelocimetryOptimisation


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Timestamp:
Jan 27, 2015, 5:09:12 PM (6 years ago)
Author:
vaillant1p
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  • Tutorial/CorrelationImageVelocimetryOptimisation

    v9 v10  
    1616It is now possible to adjust the search range, using prior knowledge on extremal velocities, see histograms displayed by '''uvmat''' in pixel  coordinates. We introduce estimated bounds on each velocity component,  [min] to -2 and [max] to 6 for ’u’ and (-3, 3) for ’v’, and press the  button '''[Search Range]'''. The optimum search ranges and shifts (for the given correlation box) are  now displayed: [33 25] and [2 0] respectively.
    1717
    18 Let us run again  PIV with '''[!CorrBoxSize]'''=[19 13] and '''[!SearchBoxSize]'''=[27 25] with '''[Shift]'''=0. (limiting ourselves to CIV1), and visualise the result with '''uvmat'''.  Many black vectors (F=-2) are obtained, showing that the search domain  is too small, so that the correlation maximum is constrained by the  limited search interval. Using  '''[!TestCiv1]''' , it can be seen that the correlation maximum is indeed on the edge of the Search box, a lot of black error flag will thus be seen on the velocity image. Then come back to the good parameters.
     18Let us run again  PIV with '''[!CorrBoxSize]'''=[19 13] and '''[!SearchBoxSize]'''=[27 25] with '''[Shift]'''=0. (limiting ourselves to CIV1), and visualise the result with '''uvmat'''.  Many black vectors (F=-2) are obtained, showing that the search domain  is too small, so that the correlation maximum is constrained by the  limited search interval. Using  '''[!TestCiv1]''' , it can be seen that the correlation maximum is indeed on the edge of the Search box, a lot of black error flags will thus be seen on the velocity image. Then come back to the good parameters.
    1919
    2020== !CorrSmooth ==