Velocity magnidute incorrect

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Pratap Pratap
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Velocity magnidute incorrect

Dear Mr. William,

I am greatful to you for developing this wonderful software. I request your help on following query:

The velocity measured externally has value of 0.1m/s while using PIVlab i am getting 0.0012 m/s. I may be wrong somewehre in calibration, but I still request you to kindly help me on this.

My camera settings is 50 fps. and for calibration 26.51 pixel is 1mm.

I have uploaded few images for your perusal:

http://s4.postimg.org/urnb03y25/00146_032.jpg
http://s4.postimg.org/ky6lu7pd9/00146_033.jpg
http://s4.postimg.org/80e8dpd0t/00146_034.jpg
http://s4.postimg.org/fy8nfcqb1/00146_035.jpg
http://s4.postimg.org/6cf2z1z59/00146_036.jpg
http://s4.postimg.org/tf6454u25/00146_037.jpg
http://s4.postimg.org/ygdi6i1il/00146_038.jpg

Kindly help on this issue.
William William
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Re: Velocity magnidute incorrect

Hi,
I had a look at the images. You won't get correct results with this kind of images. Your jet needs to be zoomed in and you need to record with more fps. At the moment there are hardly any particles that are moving. Just three or four particles are in the jet, this is not enough for particle image velocimetry.

Please consider donating for the PIVlab project:
http://paypal.me/pools/c/81Y8wBVi4y

The developer needs to update to a recent Matlab release in order to keep the project running.

William William
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Re: Velocity magnidute incorrect

In reply to this post by Pratap
Additionally, I just noticed that many of your images are totally identical. Your camera seems to save frame duplicates instead of filming with true 50 fps (e.g. 00146_032.jpg and 00146_033.jpg are identical).

Please consider donating for the PIVlab project:
http://paypal.me/pools/c/81Y8wBVi4y

The developer needs to update to a recent Matlab release in order to keep the project running.

Pratap Pratap
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Re: Velocity magnidute incorrect

Hi Mr. William,

Thanks a lot for guiding me on this. Your valuable comments have given me clear picture about anomaly in my experiment.

Regards...
Pratap