C3D files incorrectly converted with matlab tool

[AUDE LEFRANC]

Hi All,

I'm using openSim 4.1 beta version (not 4.0, as suggested by tag). I installed it recently, right before 4.1 was actually released. I can't imagine there would be a big difference between my version and the normal 4.1 version.

I'm trying to convert C3D files into TRC and MOT files. It turns out there were some issues exporting the MOT files. The moments of the right force plate in all my trials were not exported, but they are present in the C3D files. Also, some of the trials were cut super short (after half a second) so I have super short MOT files.
TRC files look just fine.

What's going on?

Thanks,
Aude

[Ayman Habib]

Hello,

Can you please clarify what matlab tool you're referring to, and if possible attach the .c3d file so we can reproduce your issue. Also did you try the same in version 4.0? Does your file contain NaNs?

Depending on when you downloaded the beta it could be different but generally we made no late changes to c3d file handling in the API.

Best regards,
-Ayman

[AUDE LEFRANC]

Hello Ayman,

Thank you for your reply!

Sorry, I should have clarified; I'm using the "c3dExport" tool that was in the matlab folder when I installed 4.1. I did not use version 4.0 because I previously had issues converting files using that version (discussed in a previous forum post). It was recommended that I use 4.1 instead.

Yes the file does have Nans. The CP data has an nan anytime someone's foot doesn't touch the place (it's recorded as nan, not zero).

I probably downloaded 4.1 within the last couple weeks, but I'll try installing the most recent release!

I tried attaching the c3d files, but it says they don't have a valid file extension? And it said the mot files were too big too attach. Essentially, I'm pretty sure they have the following format: 9 columns for each foot, first three are forces (x, y, z), next 3 are cp (x, y, z), following 3 are moments. There are 18 columns total. There are some nan values.

Hope this helps!

Best,
Aude

[Ayman Habib]

Hi Aude,

Please file a bug so you can attach the .c3d file and we'll check it out. Use the link from the application's Help->Report Bug
and you'll be able to attach the files you need and describe the steps to reproduce.

Best regards,
-Ayman

[AUDE LEFRANC]

Hi Ayman,

Thank you! I went ahead and submitted a bug with attached C3D and MOT files.
Let me know if you have any additional questions.

Best,
Aude