Spurious velocity vectors

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Murad Murad
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Spurious velocity vectors

I used PIVlab to analyse soil deformations of a laboratory model (Bearing Capacity), but I'm getting some velocity vectors in a place I'm not expecting that.Is there any possible method to remove them manually. I tried to remove bad vectors, however they are placed randomly and I can only select vectors which fit the selection rectangle. I'm sure that there should be no soil deformation/movement in that region but I think they are due to change in lighting conditions.
Tobi Tobi
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Re: Spurious velocity vectors

I hope I understand this correctly: You find movement in an area of your picture that shouldnt have movement.
Two possibilities that I see:
- either mask areas that are not interesting (i.e. where you dont expect movement) BEFORE the PIV analysis. Hit "Analysis options --> Exclusions". Draw your mask. Masks are polygonal.
- you can select the vectors that should be extracted and used in your evaluation AFTER the PIV analysis. Hit "Extractions --> parameters from area". Choose the parameter you need to extract. Then draw your area from which you want to extract. This again is a polygon.

These methods dont work, however, if your (un)interesting area moves throughout your take. I think for you the first method should do it. The masked area then contains small red Xes instead of vectors. Also, it's less effort for the processor.

Best regards,
Tobi
Tobi Tobi
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Re: Spurious velocity vectors

If you do masks, dont forget to spread them onto all your pictures or make a mask for each picture individually.