Extraction of the right hand from GRAB

[Borzyszkowski]

Hello!

For my project, I would like to use only a single (right hand) with GRAB. I plugged MANO as a model type instead of SMPL-X, however I'm facing two problems:

1) Inaccuracies Although the same GRAB data is used, MANO is visibly less accurate for the hand-object interaction than SMPL-X.

Full body:

Right hand:

Everything seems to be in place from my code level, so I'm assuming the model itself makes a difference. I also get a warning which is probably the reason: WARNING: You are using a MANO model, with only 10 shape coefficients.

Is there a way to get the exact same hand movement with MANO as with the hand in SMPL-X?

2) Contact forces I would like to extract the contact forces only for the right hand. They are saved in two dictionaries:

• seq_data['contact']['object']
• seq_data['contact']['body']

For the object dictionary, I can extract values for the right hand according to the table that shows mapping between the contact number and each body joint (values greater than 40).

However in case of the body dictionary, there's an error with dimensions: dimension is 778 but corresponding boolean dimension is 10475. Specifically, MANO expects the size 778 while the list has 10475 values as originally for SMPL-X. I assume that I should take only 778 values from this list that are relevant for the right hand, but this is not clear.

Is there a simple way to extract the contact forces only for the hand?

Thank you, Bartek

[Borzyszkowski]

I was able to solve 1) using flat_hand_mean option from SMPL-X.

Answer for 2) would be still helpful though.

Thank you, Bartek

[Borzyszkowski]

I managed to solve the point 2) by downloading 'MANO and FLAME vertex indices' from SMPL-X website. I also found this presentation helpful.