Knee tracking / Dartfish or other motion analysis software

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Marin Maniac
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Joined: Wed Mar 18, 2009 15:09 pm

Knee tracking / Dartfish or other motion analysis software

Postby Marin Maniac » Sun Nov 18, 2012 11:59 am

Had a bit of spare time on my hands and took some small videos to try and suss out what my knees are doing with different insoles and varus wedges.

Anyone know of any free motion analysis software that has a trajectory function like Dartfish pro/team that can show the trajectory of ones knee tracking?

Or

Does any kind soul have said software that after I've furnished them with the .avi files and some beer tokens, could have a look and tell me what my knees are doing?

TIA.

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sungod
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Re: Knee tracking / Dartfish or other motion analysis softwa

Postby sungod » Sun Nov 18, 2012 13:22 pm

if you set the camera up so that the optical axis is at mid-height of your knee on the pedal stroke, parallel to the ground, and to the vertical plane bisecting the pedal (i.e. so it's about head-on to the leg of interest for the shot), and attach a marker to your knee (or put a dot on it with a marker pen)

then it's straightforward to check tracking to see if it's going in/out at the top for instance

on playback you can zoom in to the knee, then either overlay a vertical line, or simply use the edge of a window as a guide

if you can fit a ruler into the shot at about knee distance you can even get a good estimate of how much absolute deviation there is

you can add markers on ankle and hips, to check for movement there

it may seem a clunky way to do it, but with care setting up the camera the results will be fine

otherwise, there are a few freeware options, for instance...

http://www.cabrillo.edu/~dbrown/tracker/

but imho the 'manual' method will show knee tracking actual vs. vertical perfectly well
my bike - faster than god's and twice as shiny

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Marin Maniac
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Re: Knee tracking / Dartfish or other motion analysis softwa

Postby Marin Maniac » Sun Nov 18, 2012 19:14 pm

Thanks for the reply. Downloaded 'tracker', but seems very involved. I know my knee doesn't track straight up and down, and I think that is partly to do with me feet needing to be moved outboard, but what I'd like to see is the trace that the knee leaves as I go through the pedal stroke.

With Dartfish you can select a point in a video say below the knee and select trajectory and the marker traces the movement of the knee through the pedal stroke.


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