Changes between Version 8 and Version 9 of Tutorial/CorrelationImageVelocimetryOptimisation
 Timestamp:
 Jan 27, 2015, 5:08:53 PM (6 years ago)
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Tutorial/CorrelationImageVelocimetryOptimisation
v8 v9 16 16 It 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. 17 17 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. Then come back to the good parameters.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. 19 19 20 20 == !CorrSmooth ==