IpiSoft MotionBuilder UE4 root axis rotation issue
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Author:  Jonas_molgaard [ Thu Mar 17, 2016 3:30 pm ]
Post subject:  IpiSoft MotionBuilder UE4 root axis rotation issue

Hi there,

I have an issue with a workflow that involves taking mocap data from IPI Mocap Studio to MotionBuilder to cleanup the data and then export it on to UE4. Since IPI does not like to use the default export of the UE4 skeleton, i have to remove the root/reference joint along with some IK joints, otherwise it will look weird. This will open up just fine in MotionBuilder where i can then clean it up and animation a bit on it. However when i want to bring it into UE4, it needs to have a root joint again, so i need to add that manually after again. But when i do that, it either makes the character lie down on his back (rotated back) or makes the axis switch from Z-up to Z-forward (or Y-down if you like). So i wonder if someone know how to work around this kind of issue... surely it must be something that people run into quite often and that can be "fixed"?

I've uploaded a video showing what i try to do, where i also explain what i do. Maybe someone can spot something im missing or doing wrong.



Author:  Jonas_molgaard [ Fri Mar 18, 2016 2:33 pm ]
Post subject:  Found a working solution

Maybe it's not the best one, but it seems to work. I've documented it on my youtube channel here.

Let me know if there's something that can be done better or easier. Otherwise i hope this will prove usefull to someone.

Part 1 - https://www.youtube.com/watch?v=oVuOtqmzSxM
Part 2 - https://www.youtube.com/watch?v=8QHo7f7UU2s


Author:  Snapz [ Sat Mar 19, 2016 11:08 am ]
Post subject:  Re: IpiSoft MotionBuilder UE4 root axis rotation issue


Maybe start here and see if you are missing any information on importing and requirements, or check box enabling.

You shouldn't have to perform all those steps to get an animation properly into UE4 from iPi.

http://docs.unrealengine.com/latest/INT ... index.html

http://docs.unrealengine.com/latest/INT ... index.html

It also looks like your export of the Mannequin is not set to proper scale using cm, it looks like it's in meters, try to re-export it from Maya as cm scale as Y-up which is what iPi uses, but you may need to rotate the root to appear front facing in iPi also.


Author:  Snapz [ Sat Mar 19, 2016 2:58 pm ]
Post subject:  Re: IpiSoft MotionBuilder UE4 root axis rotation issue


I found the SK Mannequin file here: https://www.dropbox.com/sh/0izkce9llhf9 ... in2.0?dl=0

I will give it a go to get it loadable inside iPi Studio correctly, but it does come in very large and rotated wrong, as UE4 uses a Z-up axis.

I will let you know if I find an optimal way to do it, but I don't have UE4 installed for client tests.


I was able to open the Mannequin file in 3ds Max and re-export it using scale as millimeters with a Y-up axis and load it in as a target character in iPi Studio and characterized it, this is what was achieved:


In theory, since I don't have UE4 installed, if I reversed this process upon export out of iPi Studio as an FBX, I should be able to import it into UE4 and things work fine also.


Well, in testing after FBX export, it seems the iPi characterization won't allow the "root" to be used, so the animation is exported fine, but isn't on a stable axis, so you would have to re-parent the hips to the root of the original file in Motion Builder or use a dummy node in 3ds Max and parent it to the hips to stabilize everything again, or retarget it back to your original Mannequin rig and plot it for export.

I am not sure how UE4 allows animation files to be imported, just as animation without the skeletal mesh, maybe that would work too.


I found this from Joe that might help explain things with the retargeting just by using the Motion Builder preset skeleton for export from iPi and importing into UE4.


I saw he didn't use a skeleton file on import into UE4 as you did, maybe that is your issue, as it creates one for you if "none" is left for that dialog and I didn't think you had to go through all you did to get an animation from iPi to work seamlessly inside UE4.

I hope any of this will help :)


Author:  Jonas_molgaard [ Mon Apr 11, 2016 5:33 am ]
Post subject:  Re: IpiSoft MotionBuilder UE4 root axis rotation issue

I ended up with something like this: https://www.youtube.com/watch?v=oVuOtqm ... -hvniY8eyP

Basically i made a modified version of the SK_Mannequin which i use for ipisoft export, and then in MotionBuilder i use that to drive another character and then plot all that onto a second skeleton which has the root node. This allows me to keep the orientation and get a fairly quick workflow from ipisoft to MotionBuilder to UE4.

edit: Just noticed i already posted the link to those videos... so just ignore :)

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