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Posted: **Fri May 27, 2011 9:40 am**

Hello everyone,

I use a different set up of marker placement from that is in the gait2392_Scale_MarkerSet.xml (both in number and position)
Now I’m gonna to modify this xml file to be adapted with my marker’s placement. I’m wondering how I can get the marker’slocation (x,y,z)? Is it just by trial and error and approximation in Marker Editor in GUI?
For example:
- <Marker name="R.Acromium">
<location>-0.03 0.44 0.15</location>
<fixed>false</fixed>
<body>torso</body>

R.Acromium is attached to body torso in position (-0.03 0.44 0.15) in respect to torso’s origin. Now about a new marker what is the scenario to find its location?

Thank you.

Posted: **Fri May 27, 2011 9:47 am**

Its easiest to work with it in the GUI. If you create a new marker in the GUI by default its with respect to the ground. Select the body you want to attach it to. And then you can manually move the marker till it ends where you want it to go.

That way you can pu the marker where you want it to go and the system will figure out the corresponding coordinate value.

Posted: **Tue May 31, 2011 10:33 am**

Hi Mehri,

Usually there're anatomical markers at some well defined bony landmarks that you can easily place and other markers that are harder to pinpoint on the model.

As Gregory suggested, you'd use the GUI to place the markers approximately where you want them, then when you run the Scale Tool you can "Adjust the model markers" based on a trc file to match the actual location based on a static trial (OpenSim would internally run an IK computation to minimize the sum of squares of marker errors).

Hope this helps,
-Ayman

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Markers Location in MarkerSet.xml

Markers Location in MarkerSet.xml

RE: Markers Location in MarkerSet.xml

RE: Markers Location in MarkerSet.xml