Question for the marker placement in scaling process

[Jiale Zhu]

Dear all,

I am trying to use this thoracoscapular model(https://simtk.org/projects/thoracoscapular) for scaling. But I am confused for the "gu" marker placement. It seems this virtual marker is in the humerus bone. How could I track the accurate position of this marker?

Thanks in advance for any advice.

Best regards,
Jiale

[Carmichael Ong]

I'm not completely familiar with this model's marker set, so this could be a good question to look up with the original paper (https://nmbl.stanford.edu/wp-content/up ... -00090.pdf) or checking in with the authors.

In general, virtual markers are typically calculated based on other markers (either through some dynamic or static motion data). More info on the different types of markers can be found in a webinar on scaling (https://youtu.be/ZG7wzvQC6eU?list=PLGBi ... -H3C&t=717)

[Jiale Zhu]

Thanks Carmichael,
I have search the marker placement in the original paper, but it wasn't mentioned. I will try to contact with authors.

For now, I finished scaling (I am not sure the method to calculate virtual markers is right or not). Then I choose a shoulder abduction movement (marker data recorded through experiment) and run IK and CMC. The muscle activation result is weird. Anterior deltoid muscle(red one) is not activated from begin to end. Also, there are several sharps in posterior deltoid muscle's curve. I checked the IK result, the angle curve seems make sense, I have no idea why muscle activation result is like this.

Do you have some advices for this?

CMC_sr1_3.png (28.09 KiB) Viewed 520 times