Current state-of-the-art in 3D human pose and shape recovery relies on deep neural networks and statistical morphable body models, such as the Skinned Multi-Person Linear model (SMPL). However, regardless of the advantages of having both body pose and shape, SMPL-based solutions have shown difficulties to predict 3D bodies accurately. This is mainly due to the unconstrained nature of SMPL, which may generate unrealistic body meshes. Because of this, regression of SMPL parameters is a difficult task, often addressed with complex regularization terms. In this paper we propose to embed SMPL within a deep model to accurately estimate 3D pose and shape from a still RGB image. We use CNN-based 3D joint predictions as an intermediate representation to regress SMPL pose and shape parameters. Later, 3D joints are reconstructed again in the SMPL output. This module can be seen as an autoencoder where the encoder is a deep neural network and the decoder is SMPL model. We refer to this as SMPL reverse (SMPLR). By implementing SMPLR as an encoder-decoder we avoid the need of complex constraints on pose and shape. Furthermore, given that in-the-wild datasets usually lack accurate 3D annotations, it is desirable to lift 2D joints to 3D without pairing 3D annotations with RGB images. Therefore, we also propose a denoising autoencoder (DAE) module between CNN and SMPLR, able to lift 2D joints to 3D and partially recover from structured error. We evaluate our method on SURREAL and Human3.6M datasets, showing improvement over SMPL-based state-of-the-art alternatives by about 4 and 25 millimeters, respectively.
It refers to regressing 3D pose directly from RGB image. Due to the nonlinear nature of the human pose, 3D pose regression without modeling correlation of joints is not a trivial task. Brau and Jiang @cite_23 estimate 3D joints and camera parameters without direct supervision on them. Instead, they use several loss functions for projected 2D joints, bones size and independent Fisher priors. Sun al @cite_21 propose a compositional loss function based on relative joints with respect to a defined kinematic tree. They separate 2D joints and depth estimation in the loss.
@cite_21 @cite_23
2953258117 2566741951
Regression based methods are not performing as well as detection based methods for human pose estimation. A central problem is that the structural information in the pose is not well exploited in the previous regression methods. In this work, we propose a structure-aware regression approach. It adopts a reparameterized pose representation using bones instead of joints. It exploits the joint connection structure to define a compositional loss function that encodes the long range interactions in the pose. It is simple, effective, and general for both 2D and 3D pose estimation in a unified setting. Comprehensive evaluation validates the effectiveness of our approach. It significantly advances the state-of-the-art on Human3.6M and is competitive with state-of-the-art results on MPII. We propose a deep convolutional neural network for 3Dhuman pose and camera estimation from monocular imagesthat learns from 2D joint annotations. The proposed networkfollows the typical architecture, but contains an additionaloutput layer which projects predicted 3D joints onto2D, and enforces constraints on body part lengths in 3D.We further enforce pose constraints using an independentlytrained network that learns a prior distribution over 3Dposes. We evaluate our approach on several benchmarkdatasets and compare against state-of-the-art approachesfor 3D human pose estimation, achieving comparable performance.Additionally, we show that our approach significantlyoutperforms other methods in cases where 3Dground truth data is unavailable, and that our network exhibitsgood generalization properties.