Stable SMPL-to-UE5 reference data for retargeting and coordinate discussions
Use this as reference data for naming, hierarchy, and coordinate-system discussions.
Do not treat this file as authority for exact final runtime transforms until validated against UE5 runtime evidence.
SMPL:
UE5:
Important:
| Index | Joint Name | Parent Index | Approximate UE5 Bone |
|---|---|---|---|
| 0 | Pelvis | -1 | pelvis |
| 1 | L_Hip | 0 | thigh_l |
| 2 | R_Hip |
| 0 |
| thigh_r |
| 3 | Spine1 | 0 | spine_01 |
| 4 | L_Knee | 1 | calf_l |
| 5 | R_Knee | 2 | calf_r |
| 6 | Spine2 | 3 | spine_02 |
| 7 | L_Ankle | 4 | foot_l |
| 8 | R_Ankle | 5 | foot_r |
| 9 | Spine3 | 6 | spine_03 |
| 10 | L_Foot | 7 | ball_l |
| 11 | R_Foot | 8 | ball_r |
| 12 | Neck | 9 | neck_01 |
| 13 | L_Collar | 9 | clavicle_l |
| 14 | R_Collar | 9 | clavicle_r |
| 15 | Head | 12 | head |
| 16 | L_Shoulder | 13 | upperarm_l |
| 17 | R_Shoulder | 14 | upperarm_r |
| 18 | L_Elbow | 16 | lowerarm_l |
| 19 | R_Elbow | 17 | lowerarm_r |
| 20 | L_Wrist | 18 | hand_l |
| 21 | R_Wrist | 19 | hand_r |
| 22 | L_Hand | 20 | unmapped / fingers |
| 23 | R_Hand | 21 | unmapped / fingers |
SMPL body pose is commonly represented as:
Interpretation:
Neutral pose convention:
When implementing or reviewing retargeting: