Adversarial Parametric Pose Prior
This addresses the issue of invalid human pose reconstructions in computer vision, offering an incremental improvement over existing methods for constraining SMPL parameters.
The paper tackles the problem of SMPL model parameters producing unrealistic human poses by learning an adversarial prior to restrict them to realistic values, resulting in improved 3D reconstruction from 2D keypoints and better pose estimates from images, outperforming a VAE-based approach.
The Skinned Multi-Person Linear (SMPL) model can represent a human body by mapping pose and shape parameters to body meshes. This has been shown to facilitate inferring 3D human pose and shape from images via different learning models. However, not all pose and shape parameter values yield physically-plausible or even realistic body meshes. In other words, SMPL is under-constrained and may thus lead to invalid results when used to reconstruct humans from images, either by directly optimizing its parameters, or by learning a mapping from the image to these parameters. In this paper, we therefore learn a prior that restricts the SMPL parameters to values that produce realistic poses via adversarial training. We show that our learned prior covers the diversity of the real-data distribution, facilitates optimization for 3D reconstruction from 2D keypoints, and yields better pose estimates when used for regression from images. We found that the prior based on spherical distribution gets the best results. Furthermore, in all these tasks, it outperforms the state-of-the-art VAE-based approach to constraining the SMPL parameters.