Changes between Version 30 and Version 31 of Tutorial/ParticleImageVelocimetry
 Timestamp:
 Jan 21, 2015, 2:20:51 PM (6 years ago)
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Tutorial/ParticleImageVelocimetry
v30 v31 106 106 '''* FIX1''': Select the ’'''FIX1'''’ operation, which eliminates some false vectors using several criteria. Use the default parameters. 107 107 108 '''* PATCH1''': Select the ’'''PATCH1'''’ operation, to interpolate the vectors on a regular grid and calculate spatial derivatives. Choose the default value 10 for the smoothing parameter '''[! !FieldSmooth]'''. You can later try different values, the smoothing effect increasing with '''!!FieldSmooth'''. Keep the default values for the other parameters.108 '''* PATCH1''': Select the ’'''PATCH1'''’ operation, to interpolate the vectors on a regular grid and calculate spatial derivatives. Choose the default value 10 for the smoothing parameter '''[!FieldSmooth]'''. You can later try different values, the smoothing effect increasing with '''!FieldSmooth'''. Keep the default values for the other parameters. 109 109 110 110 '''* CIV2''': Select the ’'''CIV2'''’ operation to improve the correlation results, using the information on local image deformation, provided by the previous knowledge on velocity spatial derivatives (calculated in patch1). Use a finer grid dx= dy=5 than for civ1. The spatial resolution can be slightly improved by decreasing the correlation box, using for instance Bx,By=(15,11). The shift of the search range is here given at each point by the prior estimate from Civ1, so that the search range can be optimized: choose [21,17] which provides a margin of 3 pixels on each side of the correlation box. Note that ’civ2’ corresponds to a new measurement from the images, the previous civ1 and patch1 operations being used only as an initial guess for the search of optimal correlations.