CoP and Markers misaligned in OpenSim 4.4

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Vincent Fohanno
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Joined: Thu May 10, 2018 10:03 am

CoP and Markers misaligned in OpenSim 4.4

Post by Vincent Fohanno » Wed Jan 04, 2023 7:33 am

Hi,

First of all, happy new year.
I am Vincent from Qualisys and I am trying to update our github repository to make it work with the OpenSim 4.4.

I am having an issue with OpenSim 4.4 where the markers and the CoP are not aligned while they are aligned in OpenSim 4.2 and OpenSim 4.3.
In all cases, I am using the same trc and mot files and I am doing the following steps:
- Select File -> Preview Experimental Data and load .trc file (marker data)
- Repeat for .mot file (force data)
- Extend the ExperimentalData nodes, use Ctrl+click to select .trc and .mot data and select Sync motions

I am attaching the trc/mot files as a zip file as well as screenshot of my issue so that you can reproduce the issue and give me some feedback.

Thank you in advance for your help

Vincent
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Thomas Uchida
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Re: CoP and Markers misaligned in OpenSim 4.4

Post by Thomas Uchida » Wed Jan 04, 2023 9:14 am

I believe what is happening is that the marker and force data are being loaded as separate "models" by the GUI. By default, models are offset when they are loaded (so that skeletons aren't displayed on top of each other). The origin of the virtual world in which each model resides can be adjusted by changing the "Model offset". Please see the "Object-Specific Commands" page in the documentation (search for "model offset" on this page): https://simtk-confluence.stanford.edu:8 ... c+Commands. The data should align if the model offsets (x,y,z) are equal.

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Vincent Fohanno
Posts: 23
Joined: Thu May 10, 2018 10:03 am

Re: CoP and Markers misaligned in OpenSim 4.4

Post by Vincent Fohanno » Wed Jan 04, 2023 9:35 am

Hi Thomas,

Great. It was the issue.
I will add a note on our repository about that.

Thank you and have a great day

Vincent

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