problem in validation. please help me

[LEE Jinguk]

I conducted squats to validate Opencap and mocap. To synchronize the two cameras, I want to set the start and end points of the squat motion, but I'm having trouble deciding which parts to use. I would like to hear your opinions.

I want to set the start and end points using position data (.trc) and include a quadratic model in the synchronized figure for my paper. The reason I want to use a quadratic model is to compare the peak angle values. When writing the paper, having at least a quadratic model is essential to accurately present the peak angle point.

so, I would like to know which points the Opencap team used to synchronize with mocap when analyzing the squat motion.

I would appreciate hearing your valuable opinions. Thank you

[Matt Petrucci]

Hi Lee,

You could consider using a relevant kinematic feature (like a joint angle) or marker position and running a cross correlation on the two signals to find the time offset.

Hope this helps,

[LEE Jinguk]

Thank you for your opinion!

Which joint angle or marker position would be appropriate? Could you tell me some examples?
I know the method about sync but can't decide joint angle or marker position...

If I did 2 or 3 squat trials, it will be fine. But unfortunately I did only one trial

[Matt Petrucci]

Hi Lee,

Using a marker that easily seen and not occluded could work (for example, the shoulder). For a joint angle, you could use knee angle since it corresponds to the primary movement.

Hope this helps,