PostureHMR: Posture Transformation for 3D Human Mesh Recovery

Human Mesh Recovery (HMR) aims to estimate the 3D human body from 2D images, which is a challenging task due to inherent ambiguities in translating 2D observations to 3D space. A novel approach called PostureHMR is proposed to leverage a multi-step diffusion-style process, which converts this task into a posture transformation from an SMPL T-pose mesh to the target mesh. To inject the learning process of posture transformation with the physical structure of the human body model, a kinematics-based forward process is proposed to interpolate the intermediate state with pose and shape decomposition. Moreover, a mesh-to-posture (M2P) decoder is designed, by combining the input of 3D and 2D mesh constraints estimated from the image to model the posture changes in the reverse process. It mitigates the difficulties of posture change learning directly from RGB pixels. To overcome the limitation of pixel-level misalignment of modeling results with the input image, a new trimap-based rendering loss is designed to highlight the areas with poor recognition. Experiments conducted on three widely used datasets demonstrate that the proposed approach outperforms the state-of-the-art methods.