Tracking the motion of spheres

  • Thread starter Shoune
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Hi,

I'm looking to do random, silly stuff with the Coriolis effect, mainly just confirming what theory predicts, using a simple rotating turntable.
My hope in doing that was to use a typical, average consumer camera, film the motion in question from above, with markers for frames of reference inside and outside the rotating turntables, and then use the video to get an x/y position graph from that.

Where it gets tricky is that I'm stumped on how to actually reliably use the video captured. I've thought about Adobe After Effects, using contrasted markers to track the motion in relation with the basic x/y coordinates of the picture, but I doubt it will manage the shifting frame of reference inside the turntable.

I know that there is quite a bit of specific software out there, but I'm looking for something that would do it automatically (i.e. lock on a specific point and not just ask me to click every single time on the right dot) and also let me specify the reference frame, and I simply can't get the search string to give me anything good in Google.

I also have available a motion capture set which is basically a CCD with LED strobes reflecting off anything interesting feeding into a computer looking at received intensity, but that means making all my system reflective, and also means I have to deal with a huge amount of noise.

I'd appreciate any input on this, thanks =)
 

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  • #2
Andy Resnick
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Check out the particle tracking routines by Eric Weeks, John Crocker, and David Grier. Their codes are openly available, and if you can't find the code, they are very nice folks and would more than likely send them to you.
 
  • #3
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Not entirely sure what you're going for here.

If you put a pen on the centre of the rotating disc and drag it outwards you will notice it curves. That will show you the path of a particle in the atmosphere due to the coriolis effect.

I assume you already understand the coriolis effect. If not, neither mine nor yours will explain it to you.

It's a bit basic but I'm not sure why you have created such a complicated setup to demonstrate such a simple concept.
 
  • #4
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I'm able to more or less derive the mathematical root of the stuff in terms of one or the other reference frame, what I'm looking for here is experimental "confirmation" of the derivation. Getting a video gives me time, and having position in both frames pretty much gives me anything else I would want.

Essentially, I'm looking for the pretty picture to put on the front page of my report, but this picture helps me show to anyone reading it the importance of the reference frames.
 

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