Motion Retargeting Tool

[gui 25]

For the folks out there looking for a way to do motion retargeting inside houdini, here´s a tease for a tool that has being working for 2 years now! In a couple of weeks I will share more info about how it works, since I don´t have plans to release it, but I will help anyone who wants to do the same - the tool doesn´t have fancy a algorithm, but works very well.

https://vimeo.com/299246872

Edited November 6, 2018 by gui

[AaronAb 7]

Looks awesome! can't wait to see how you achieved this!

[xquisite 0]

Hey, 

 

it's been a few months and I was wondering if you will ever release some instructions on retargeting within HD? Your tool looks awesome and is exactly what I need to achieve. 

Cheers,

George

[gui 25]

7 hours ago, xquisite said:

Hey, 

 

it's been a few months and I was wondering if you will ever release some instructions on retargeting within HD? Your tool looks awesome and is exactly what I need to achieve. 

Cheers,

George

Hi @xquisite , I, unfortunately, don´t have plans to release it in the near future, since It needs a major rewrite of the code and some tests using chops instead of python to do the retarget.

Most of my code was for handling errors that came from the CMU mocaps and for automating stuff. The core logic of the retarget I build it´s just linear algebra, so nothing "intelligent" for retargeting here. If you need help for building the retarget, just drop the scene and I will help you.

[xquisite 0]

hey @gui, thanks for responding so fast. I was just google-ing retargeting within Houdini and found your thread, because i am just getting my feet wet with animation within Houdini.

I have a long animation in C4D which i export either as alembic or fbx and import it into houdini. I place a character I rigged in Houdini into the scene and basically want to retarget that animation to that character. To be honest I don't even where to start with building up the network and asking you to go over the scene file would be very time-consuming for you I suppose. Maybe you have some tips where I can find some documentation on that, my search came up with nothing. And thanks a lot for your offer to help, appreciate it.

[lobao 1]

Guilherme, how are you?

Come on, I have:

- Mocap captured by rococo software and exporting in an FBX. The animation was captured from a person with 1.80.

- I have a model that has a size different from my mocap, it should have its 1.65. It's in T-pose and or A-pose.

- I already tried to do the retarget in houdini using the CHOP channel and using the feath parameters, and the time I use it, my model tries to adjust to the size of my mocap, distorting the whole mesh of the animation.

[Atom 934]

You could try the shelf tool Blend Constraint to bind the mocap skeleton to the rig skeleton.

Goldfarb explains here.
https://www.sidefx.com/forum/topic/55681/#post-250676

[gui 25]

The overall idea is to "bind" the TPoses and follow each bone rotation from there. There are more intelligent approaches out there, but far harder to implement.

A simple parent constraint from the TPose should work.

In my setup, I did that using python objs to store the transformations and a python asset to automate the placing of constraints, but It still needs human input to link the source bone to the target one.

One note: I don´t like FBX very much, because it tries to mimic a joint approach and put the deformations in the nulls, instead of bones. It sometimes gives strange gimbal problems.

My usual workflow is to convert the fbx to bhv and then use mcbiovision to create a clean houdini rig internally.

[lobao 1]

Thank you guys, but I still have not been able to do it.

I already managed to export my mocap in the bhv format and then I converted it into .bclip and .cmd, and I can not get the other model to follow this animation.

Note: I do not know anything about python so I'm kind of lost.

I accessed the link that @Atom posted above, and I looked for Goldfarb's answers .. and I was even more lost.

Is there any other less complicated option to do this re-targeting?

[gui 25]

Send me a file and I will show how to do it.

[lobao 1]

https://www.dropbox.com/s/vyvkrygn21evd0t/retargeting.zip?dl=0

[gui 25]

On 13/05/2019 at 6:02 PM, lobao said:

https://www.dropbox.com/s/vyvkrygn21evd0t/retargeting.zip?dl=0

Hi, sorry for the late reply, but I didn´t have much time to review that. I put some notes in the file, but in a nutshell, I just used paren_blend  constraint to match de movement. The idea is to use python to automate the constraints creation.ap_mocap_retarget_share_v003.hiplc