人机协作

Knowledge distillation methods have recently shown to be a promising direction to speedup the synthesis of large-scale diffusion models by requiring only a few inference steps. While several powerful distillation methods were recently proposed the overall quality of student samples is typically lower compared to the teacher ones which hinders their practical usage. In this work we investigate the relative quality of samples produced by the teacher text-to-image diffusion model and its distilled student version. As our main empirical finding we discover that a noticeable portion of student samples exhibit superior fidelity compared to the teacher ones despite the approximate nature of the student. Based on this finding we propose an adaptive collaboration between student and teacher diffusion models for effective text-to-image synthesis. Specifically the distilled model produces an initial image sample and then an oracle decides whether it needs further improvements with the teacher model. Extensive experiments demonstrate that the designed pipeline surpasses state-of-the-art text-to-image alternatives for various inference budgets in terms of human preference. Furthermore the proposed approach can be naturally used in popular applications such as text-guided image editing and controllable generation.

Various applications require high-fidelity and artifact-free 3D human reconstructions. However current implicit function-based methods inevitably produce artifacts while existing deformation methods are difficult to reconstruct high-fidelity humans wearing loose clothing. In this paper we propose a two-stage deformation method named Vertex Shift (VS) for reconstructing clothed 3D humans from single images. Specifically VS first stretches the estimated SMPL-X mesh into a coarse 3D human model using shift fields inferred from normal maps then refines the coarse 3D human model into a detailed 3D human model via a graph convolutional network embedded with implicit-function-learned features. This "stretch-refine" strategy addresses large deformations required for reconstructing loose clothing and delicate deformations for recovering intricate and detailed surfaces achieving high-fidelity reconstructions that faithfully convey the pose clothing and surface details from the input images. The graph convolutional network's ability to exploit neighborhood vertices coupled with the advantages inherited from the deformation methods ensure VS rarely produces artifacts like distortions and non-human shapes and never produces artifacts like holes broken parts and dismembered limbs. As a result VS can reconstruct high-fidelity and artifact-less clothed 3D humans from single images even under scenarios of challenging poses and loose clothing. Experimental results on three benchmarks and two in-the-wild datasets demonstrate that VS significantly outperforms current state-of-the-art methods. The code and models of VS are available for research purposes at https://github.com/starVisionTeam/VS.

Human image editing includes tasks like changing a person's pose their clothing or editing the image according to a text prompt. However prior work often tackles these tasks separately overlooking the benefit of mutual reinforcement from learning them jointly. In this paper we propose UniHuman a unified model that addresses multiple facets of human image editing in real-world settings. To enhance the model's generation quality and generalization capacity we leverage guidance from human visual encoders and introduce a lightweight pose-warping module that can exploit different pose representations accommodating unseen textures and patterns. Furthermore to bridge the disparity between existing human editing benchmarks with real-world data we curated 400K high-quality human image-text pairs for training and collected 2K human images for out-of-domain testing both encompassing diverse clothing styles backgrounds and age groups. Experiments on both in-domain and out-of-domain test sets demonstrate that UniHuman outperforms task-specific models by a significant margin. In user studies UniHuman is preferred by the users in an average of 77% of cases. Our project is available at https://github.com/NannanLi999/UniHuman.

We address the problem of regressing 3D human pose and shape from a single image with a focus on 3D accuracy. The current best methods leverage large datasets of 3D pseudo-ground-truth (p-GT) and 2D keypoints leading to robust performance. With such methods however we observe a paradoxical decline in 3D pose accuracy with increasing 2D accuracy. This is caused by biases in the p-GT and the use of an approximate camera projection model. We quantify the error induced by current camera models and show that fitting 2D keypoints and p-GT accurately causes incorrect 3D poses. Our analysis defines the invalid distances within which minimizing 2D and p-GT losses is detrimental. We use this to formulate a new loss "Threshold-Adaptive Loss Scaling" (TALS) that penalizes gross 2D and p-GT errors but not smaller ones. With such a loss there are many 3D poses that could equally explain the 2D evidence. To reduce this ambiguity we need a prior over valid human poses but such priors can introduce unwanted bias. To address this we exploit a tokenized representation of human pose and reformulate the problem as token prediction. This restricts the estimated poses to the space of valid poses effectively improving robustness to occlusion. Extensive experiments on the EMDB and 3DPW datasets show that our reformulated loss and tokenization allows us to train on in-the-wild data while improving 3D accuracy over the state-of-the-art. Our models and code are available for research at https://tokenhmr.is.tue.mpg.de.

To adequately utilize the available image evidence in multi-view video-based avatar modeling we propose TexVocab a novel avatar representation that constructs a texture vocabulary and associates body poses with texture maps for animation. Given multi-view RGB videos our method initially back-projects all the available images in the training videos to the posed SMPL surface producing texture maps in the SMPL UV domain. Then we construct pairs of human poses and texture maps to establish a texture vocabulary for encoding dynamic human appearances under various poses. Unlike the commonly used joint-wise manner we further design a body-part-wise encoding strategy to learn the structural effects of the kinematic chain. Given a driving pose we query the pose feature hierarchically by decomposing the pose vector into several body parts and interpolating the texture features for synthesizing fine-grained human dynamics. Overall our method is able to create animatable human avatars with detailed and dynamic appearances from RGB videos and the experiments show that our method outperforms state-of-the-art approaches.

Unsupervised visible-infrared person re-identification (US-VI-ReID) centers on learning a cross-modality retrieval model without labels reducing the reliance on expensive cross-modality manual annotation. Previous US-VI-ReID works gravitate toward learning cross-modality information with the deep features extracted from the ultimate layer. Nevertheless interfered by the multiple discrepancies solely relying on deep features is insufficient for accurately learning modality-invariant features resulting in negative optimization. The shallow feature from the shallow layers contains nuanced detail information which is critical for effective cross-modality learning but is disregarded regrettably by the existing methods. To address the above issues we design a Shallow-Deep Collaborative Learning (SDCL) framework based on the transformer with shallow-deep contrastive learning incorporating Collaborative Neighbor Learning (CNL) and Collaborative Ranking Association (CRA) module. Specifically CNL unveils the intrinsic homogeneous and heterogeneous collaboration which are harnessed for neighbor alignment enhancing the robustness in a dynamic manner. Furthermore CRA associates the cross-modality labels with the ranking association between shallow and deep features furnishing valuable supervision for cross-modality learning. Extensive experiments validate the superiority of our method even outperforming certain supervised counterparts.

The field of 3D detailed human mesh reconstruction has made significant progress in recent years. However current methods still face challenges when used in industrial applications due to unstable results low-quality meshes and a lack of UV unwrapping and skinning weights. In this paper we present SHERT a novel pipeline that can reconstruct semantic human meshes with textures and high-precision details. SHERT applies semantic- and normal-based sampling between the detailed surface (e.g. mesh and SDF) and the corresponding SMPL-X model to obtain a partially sampled semantic mesh and then generates the complete semantic mesh by our specifically designed self-supervised completion and refinement networks. Using the complete semantic mesh as a basis we employ a texture diffusion model to create human textures that are driven by both images and texts. Our reconstructed meshes have stable UV unwrapping high-quality triangle meshes and consistent semantic information. The given SMPL-X model provides semantic information and shape priors allowing SHERT to perform well even with incorrect and incomplete inputs. The semantic information also makes it easy to substitute and animate different body parts such as the face body and hands. Quantitative and qualitative experiments demonstrate that SHERT is capable of producing high-fidelity and robust semantic meshes that outperform state-of-the-art methods.

Conditional human motion generation is an important topic with many applications in virtual reality gaming and robotics. While prior works have focused on generating motion guided by text music or scenes these typically result in isolated motions confined to short durations. Instead we address the generation of long continuous sequences guided by a series of varying textual descriptions. In this context we introduce FlowMDM the first diffusion-based model that generates seamless Human Motion Compositions (HMC) without any postprocessing or redundant denoising steps. For this we introduce the Blended Positional Encodings a technique that leverages both absolute and relative positional encodings in the denoising chain. More specifically global motion coherence is recovered at the absolute stage whereas smooth and realistic transitions are built at the relative stage. As a result we achieve state-of-the-art results in terms of accuracy realism and smoothness on the Babel and HumanML3D datasets. FlowMDM excels when trained with only a single description per motion sequence thanks to its Pose-Centric Cross-ATtention which makes it robust against varying text descriptions at inference time. Finally to address the limitations of existing HMC metrics we propose two new metrics: the Peak Jerk and the Area Under the Jerk to detect abrupt transitions.

Monocular 3D human mesh estimation is an ill-posed problem characterized by inherent ambiguity and occlusion. While recent probabilistic methods propose generating multiple solutions little attention is paid to obtaining high-quality estimates from them. To address this limitation we introduce ScoreHypo a versatile framework by first leverages our novel HypoNet to generate multiple hypotheses followed by employing a meticulously designed scorer ScoreNet to evaluate and select high-quality estimates. ScoreHypo formulates the estimation process as a reverse denoising process where HypoNet produces a diverse set of plausible estimates that effectively align with the image cues. Subsequently ScoreNet is employed to rigorously evaluate and rank these estimates based on their quality and finally identify superior ones. Experimental results demonstrate that HypoNet outperforms existing state-of-the-art probabilistic methods as a multi-hypothesis mesh estimator. Moreover the estimates selected by ScoreNet significantly outperform random generation or simple averaging. Notably the trained ScoreNet exhibits generalizability as it can effectively score existing methods and significantly reduce their errors by more than 15%. Code and models are available at https://xy02-05.github.io/ScoreHypo.

We present Score-Guided Human Mesh Recovery (ScoreHMR) an approach for solving inverse problems for 3D human pose and shape reconstruction. These inverse problems involve fitting a human body model to image observations traditionally solved through optimization techniques. ScoreHMR mimics model fitting approaches but alignment with the image observation is achieved through score guidance in the latent space of a diffusion model. The diffusion model is trained to capture the conditional distribution of the human model parameters given an input image. By guiding its denoising process with a task-specific score ScoreHMR effectively solves inverse problems for various applications without the need for retraining the task-agnostic diffusion model. We evaluate our approach on three settings/applications. These are: (i) single-frame model fitting; (ii) reconstruction from multiple uncalibrated views; (iii) reconstructing humans in video sequences. ScoreHMR consistently outperforms all optimization baselines on popular benchmarks across all settings. We make our code and models available on the project website: https://statho.github.io/ScoreHMR.

Long-term and accurate forecasting is the long-standing pursuit of the human motion prediction task. Existing methods typically suffer from dramatic degradation in prediction accuracy with the increasing prediction horizon. It comes down to two reasons:1? Insufficient numerical stability.Unforeseen high noise and complex feature relationships in the data. 2? Inadequate modeling stability. Unreasonable step sizes and undesirable parameter updates in the prediction.In this paper we design a novel and symplectic integral-inspired framework named symplectic integral neural network (SINN) which engages symplectic trajectories to optimize the pose representation and employs a stable symplectic operator to alternately model the dynamic context. Specifically we design a Symplectic Representation Encoder that performs on enhanced human pose representation to obtain trajectories on the symplectic manifold ensuring numerical stability based on Hamiltonian mechanics and symplectic spatial splitting algorithm. We further present the Symplectic Temporal Aggregation module in the light of the symplectic temporal splitting algorithm which splits the long-term prediction into multiple accurate short-term predictions generated by a symplectic operator to secure modeling stability. Moreover our approach is model-agnostic and can be efficiently integrated with different physical dynamics models.The experimental results demonstrate that our method achieves the new state-of-the-art outperforming existing methods by large margins:20.1%on Human3.6M16.7%on CUM Mocap and 10.2% on 3DPW.

Humans constantly interact with their surrounding environments. Current human-centric generative models mainly focus on synthesizing humans plausibly interacting with static scenes and objects while the dynamic human action-reaction synthesis for ubiquitous causal human-human interactions is less explored. Human-human interactions can be regarded as asymmetric with actors and reactors in atomic interaction periods. In this paper we comprehensively analyze the asymmetric dynamic synchronous and detailed nature of human-human interactions and propose the first multi-setting human action-reaction synthesis benchmark to generate human reactions conditioned on given human actions. To begin with we propose to annotate the actor-reactor order of the interaction sequences for the NTU120 InterHuman and Chi3D datasets. Based on them a diffusion-based generative model with a Transformer decoder architecture called ReGenNet together with an explicit distance-based interaction loss is proposed to predict human reactions in an online manner where the future states of actors are unavailable to reactors. Quantitative and qualitative results show that our method can generate instant and plausible human reactions compared to the baselines and can generalize to unseen actor motions and viewpoint changes.

Comprehensive capturing of human motions requires both accurate captures of complex poses and precise localization of the human within scenes. Most of the HPE datasets and methods primarily rely on RGB LiDAR or IMU data. However solely using these modalities or a combination of them may not be adequate for HPE particularly for complex and fast movements. For holistic human motion understanding we present RELI11D a high-quality multimodal human motion dataset involves LiDAR IMU system RGB camera and Event camera. It records the motions of 10 actors performing 5 sports in 7 scenes including 3.32 hours of synchronized LiDAR point clouds IMU measurement data RGB videos and Event steams. Through extensive experiments we demonstrate that the RELI11D presents considerable challenges and opportunities as it contains many rapid and complex motions that require precise location. To address the challenge of integrating different modalities we propose LEIR a multimodal baseline that effectively utilizes LiDAR Point Cloud Event stream and RGB through our cross-attention fusion strategy. We show that LEIR exhibits promising results for rapid motions and daily motions and that utilizing the characteristics of multiple modalities can indeed improve HPE performance. Both the dataset and source code will be released publicly to the research community fostering collaboration and enabling further exploration in this field.

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.

Camera-parameter-free multi-view pose estimation is an emerging technique for 3D human pose estimation (HPE). They can infer the camera settings implicitly or explicitly to mitigate the depth uncertainty impact showcasing significant potential in real applications. However due to the limited camera setting diversity in the available datasets the inferred camera parameters are always simply hardcoded into the model during training and not adaptable to the input in inference making the learned models cannot generalize well under unseen camera settings. A natural solution is to artificially synthesize some samples i.e. 2D-3D pose pairs under massive new camera settings. Unfortunately to prevent over-fitting the existing camera setting the number of synthesized samples for each new camera setting should be comparable with that for the existing one which multiplies the scale of training and even makes it computationally prohibitive. In this paper we propose a novel HPE approach under the invariant risk minimization (IRM) paradigm. Precisely we first synthesize 2D poses from myriad camera settings. We then train our model under the IRM paradigm which targets at learning a common optimal model across all camera settings and thus enforces the model to automatically learn the camera parameters based on the input data. This allows the model to accurately infer 3D poses on unseen data by training on only a handful of samples from each synthesized setting and thus avoid the unbearable training cost increment. Another appealing feature of our method is that benefited from the capability of IRM in identifying the invariant features its performance on the seen camera settings is enhanced as well. Comprehensive experiments verify the superiority of our approach.

Recent advances in text-to-image generation have made remarkable progress in synthesizing realistic human photos conditioned on given text prompts. However existing personalized generation methods cannot simultaneously satisfy the requirements of high efficiency promising identity (ID) fidelity and flexible text controllability. In this work we introduce PhotoMaker an efficient personalized text-to-image generation method which mainly encodes an arbitrary number of input ID images into a stack ID embedding for preserving ID information. Such an embedding also empowers our method to be applied in many interesting scenarios such as when replacing the corresponding class word and when combining the characteristics of different identities. Besides to better drive the training of our PhotoMaker we propose an ID-oriented data creation pipeline to assemble the training data. Under the nourishment of the dataset constructed through the proposed pipeline our PhotoMaker demonstrates comparable performance to test-time fine-tuning-based methods yet provides significant speed improvements strong generalization capabilities and a wide range of applications.

Human avatar has become a novel type of 3D asset with various applications. Ideally a human avatar should be fully customizable to accommodate different settings and environments. In this work we introduce NECA an approach capable of learning versatile human representation from monocular or sparse-view videos enabling granular customization across aspects such as pose shadow shape lighting and texture. The core of our approach is to represent humans in complementary dual spaces and predict disentangled neural fields of geometry albedo shadow as well as an external lighting from which we are able to derive realistic rendering with high-frequency details via volumetric rendering. Extensive experiments demonstrate the advantage of our method over the state-of-the-art methods in photorealistic rendering as well as various editing tasks such as novel pose synthesis and relighting. Our code is available at https://github.com/iSEE-Laboratory/NECA.

In this work we aim to improve the 3D reasoning ability of Transformers in multi-view 3D human pose estimation. Recent works have focused on end-to-end learning-based transformer designs which struggle to resolve geometric information accurately particularly during occlusion. Instead we propose a novel hybrid model MVGFormer which has a series of geometric and appearance modules organized in an iterative manner. The geometry modules are learning-free and handle all viewpoint-dependent 3D tasks geometrically which notably improves the model's generalization ability. The appearance modules are learnable and are dedicated to estimating 2D poses from image signals end-to-end which enables them to achieve accurate estimates even when occlusion occurs leading to a model that is both accurate and generalizable to new cameras and geometries. We evaluate our approach for both in-domain and out-of-domain settings where our model consistently outperforms state-of-the-art methods and especially does so by a significant margin in the out-of-domain setting. We will release the code and models: https://github.com/XunshanMan/MVGFormer.

Predicting future human pose is a fundamental application for machine intelligence which drives robots to plan their behavior and paths ahead of time to seamlessly accomplish human-robot collaboration in real-world 3D scenarios. Despite encouraging results existing approaches rarely consider the effects of the external scene on the motion sequence leading to pronounced artifacts and physical implausibilities in the predictions. To address this limitation this work introduces a novel multi-modal sense-informed motion prediction approach which conditions high-fidelity generation on two modal information: external 3D scene and internal human gaze and is able to recognize their salience for future human activity. Furthermore the gaze information is regarded as the human intention and combined with both motion and scene features we construct a ternary intention-aware attention to supervise the generation to match where the human wants to reach. Meanwhile we introduce semantic coherence-aware attention to explicitly distinguish the salient point clouds and the underlying ones to ensure a reasonable interaction of the generated sequence with the 3D scene. On two real-world benchmarks the proposed method achieves state-of-the-art performance both in 3D human pose and trajectory prediction. More detailed results are available on the page: https://sites.google.com/view/cvpr2024sif3d.

We introduce Mind Artist (MindArt) a novel and efficient neural decoding architecture to snap artistic photographs from our mind in a controllable manner. Recently progress has been made in image reconstruction with non-invasive brain recordings but it's still difficult to generate realistic images with high semantic fidelity due to the scarcity of data annotations. Unlike previous methods this work casts the neural decoding into optimal transport (OT) and representation decoupling problems. Specifically under discrete OT theory we design a graph matching-guided neural representation learning framework to seek the underlying correspondences between conceptual semantics and neural signals which yields a natural and meaningful self-supervisory task. Moreover the proposed MindArt structured with multiple stand-alone modal branches enables the seamless incorporation of semantic representation into any visual style information thus leaving it to have multi-modal reconstruction and training-free semantic editing capabilities. By doing so the reconstructed images of MindArt have phenomenal realism both in terms of semantics and appearance. We compare our MindArt with leading alternatives and achieve SOTA performance in different decoding tasks. Importantly our approach can directly generate a series of stylized "mind snapshots" w/o extra optimizations which may open up more potential applications. Code is available at https://github.com/JxuanC/MindArt.