HybrIK
Twist-and-swing inverse kinematics: pixel-aligned SMPL meshes from a single image, CVPR 2021.
About
HybrIK bridges two camps that used to fight: 3D keypoint methods (accurate but anatomically implausible) and body-mesh methods (realistic but misaligned). It predicts accurate 3D joints, then converts them to SMPL joint rotations with a hybrid inverse-kinematics solve — the swing component analytically from the joints, the twist component from a neural network.
The result is a pixel-aligned 3D body mesh that beat the previous state of the art by a wide margin on 3DPW. The code ships with pretrained HRNet-W48 and ResNet-34 backbones, a Blender add-on, and an AlphaPose integration for multi-person demos; HybrIK-X (TPAMI 2025) extends the idea to whole-body mesh recovery.
Specs
Context window
Pricing
Free quota
API access
Weights
Released
Benchmarks
Provider-reported (CVPR 2021 paper): outperformed all previous methods by 13.2 mm MPJPE and 21.9 mm PVE on the 3DPW dataset. No independent published benchmarks were found.
Provider-reported unless a source says otherwise. Benchmarks are marketing-adjacent by nature — treat them as directional.
Use cases
Trust score — 7/10
Scored 7/10 (verified, metrics-v1). Evidence: peer-reviewed CVPR 2021 paper by named SJTU researchers; public code with pretrained HRNet/ResNet models and a Blender add-on; continued via HybrIK-X (TPAMI 2025). Strengths: strong venue, large reported gains on 3DPW, practical tooling. Docked for: (1) I could not verify the exact license of the release in this pass; (2) repo activity slowed after 2022. License: not verified — treat as research-use pending confirmation.
How the trust score is built
Full methodology →- Adoption · stars/downloads, log-scaled vs peers
- 8.0/10
- Maintenance · recency, releases, issue load
- 5.0/10
- Openness · license + docs
- 6.0/10
- Manual review · sanity read + red-flag check
- 8.0/10
- · CVPR 2021 (Li, Xu, Chen, Bian, Yang, Lu; SJTU MVIG); hybrid analytical-neural IK, twist-and-swing decomposition.
- · Provider-claimed +13.2mm MPJPE / +21.9mm PVE over prior SOTA on 3DPW.
- · Repo activity slowed after 2022; HybrIK-X (TPAMI 2025) is the continuation; Blender add-on + AlphaPose integration.