SMPL to FBX

I can convert motions in SMPL format into FBX files.

Steps

1. Install Python FBX.
2. Download the SMPL fbx model for unity. Keep the male model SMPL_m_unityDoubleBlends_lbs_10_scale5_207_v1.0.0.fbx.
3. pip install -r requirements.txt
4. Here's the file structure:

   <root>
   |--Convert.py
   |--SmplObject.py
   |--FbxReadWriter.py
   |--<pkl_path>/
   |  |--*.pkl
   |--<fbx_path>/
   |  |--SMPL_m_unityDoubleBlends_lbs_10_scale5_207_v1.0.0.fbx
   |--<output_path>/
   

5. python3 Convert.py --input_pkl_base <pkl_path> --fbx_source_path <fbx_path>/SMPL_m_unityDoubleBlends_lbs_10_scale5_207_v1.0.0.fbx --output_base <output_path> to start converting.

What's inside the pkl file?

A pkl file contains a dictionary with two keys: smpl_poses and smpl_trans. There's a sample pkl file in ./Pkls/sample.pkl.

• Dict["smpl_poses"] : A (N, 72) ndarray, where N is the frame number.
  • Joint order:

    0:Pelves
    1:L hip
    2:R hip"
    3:Spine1"
    4:L_Knee"
    5:R_Knee"
    6:Spine2"
    7:L_Ankle"
    8:R_Ankle"
    9:Spine3"
    10:L_Foot"
    11:R_Foot"
    12:Neck"
    13:L_Collar"
    14:R_Collar"
    15:Head"
    16:L_Shoulder"
    17:R_Shoulder"
    18:L_Elbow"
    19:R_Elbow"
    20:L_Wrist"
    21:R_Wrist"
    22:L_Hand"
    23:R_Hand"
    

  • 72 is from 24joints*3; 3 is the dimension for the rotation vector of each joint.
• Dict["smpl_trans"]: A (N, 3) ndarray. The translation of the Pelvis in each frame.
• Basically following the AIST++ naming rule. The code is designed specifically to convert the AIST++ dance motions into fbx files.

Appendix

I got a translation vector [d0, d1, d2] of a frame. How do I assign each dimension to the correct axis?

Follow this order:

Bones

bones=[(0,1), (1,4), (4,7), (7,10), # R leg
       (0,2), (2,5), (5,8), (8,11), # L leg
       (0,3), (3,6), (6,9), # Spine
       (9,12), (12,15), # Head
       (9,13), (13,16), (16,18), (18,20), (20,22), # R arm
       (9,14), (14,17), (17,19), (19,21), (21,23)] # L arm