As a prevailing post-processing tool for image retrieval, re-ranking typically leverages high-confidence retrieved samples to refine the initial ranking list. However, a significant challenge persists: existing re-ranking methods are computationally intensive, leading to impractical time costs for real-world applications. To overcome this limitation, we first review current re-ranking techniques and then introduce a novel real-time approach by reformulating the re-ranking process as a highly parallel Graph Neural Network (GNN). Specifically, we decompose the traditional neighbor-based re-ranking into two distinct stages: retrieving high-quality gallery samples and refining neighbor similarity. We propose that the first stage can be effectively replaced by constructing a k-nearest neighbor (knn) graph, while the second stage can be implemented by propagating messages within this graph. In practice, since the knn graph is sparse, the GNN only considers a limited number of vertices and their connected edges, enabling efficient updates of vertex features. We validate the effectiveness and efficiency of our approach through extensive experiments on five datasets. For example, on the Market-1501 dataset, our method accelerates the re-ranking process to 9.4 ms using a single K40m GPU. Additionally, we observe similar acceleration results on the other four retrieval benchmarks, Paris-6k, Oxford-5k, VeRi-776, and University-1652, while maintaining competitive performance.

Single-view textured human reconstruction aims to reconstruct a clothed 3D digital human by inputting a monocular 2D image. Existing approaches include feed-forward methods, limited by scarce 3D human data, and diffusion-based methods, prone to erroneous 2D hallucinations. To address these issues, we propose a novel SMPL normal map Equipped 3D Human Reconstruction (SEHR) framework, integrating a pretrained large 3D reconstruction model with human geometry prior. SEHR performs single-view human reconstruction without using a preset diffusion model in one forward propagation. Concretely, SEHR consists of two key components: SMPL Normal Map Guidance (SNMG) and SMPL Normal Map Constraint (SNMC). SNMG incorporates SMPL normal maps into an auxiliary network to provide improved body shape guidance. SNMC enhances invisible body parts by constraining the model to predict an extra SMPL normal Gaussians. Extensive experiments on two benchmark datasets demonstrate that SEHR outperforms existing state-of-the-art methods.

Abstract We study the problem of creating high-fidelity and animatable 3D avatars from only textual descriptions. Existing text-to-avatar methods are either limited to static avatars which cannot be animated or struggle to generate animatable avatars with promising quality and precise pose control. To address these limitations, we propose AvatarStudio, a generative model that yields explicit textured 3D meshes for animatable human avatars. Specifically, AvatarStudio proposes to incorporate articulation modeling into the explicit mesh representation to support high-resolution rendering and avatar animation. To ensure view consistency and pose controllability of the resulting avatars, we introduce a simple-yet-effective 2D diffusion model conditioned on DensePose for Score Distillation Sampling supervision. By effectively leveraging the synergy between the articulated mesh representation and DensePose-conditional diffusion model, AvatarStudio can create high-quality avatars from text ready for animation. Furthermore, it is competent for many applications, e.g., multimodal avatar animations and style-guided avatar creation. Please refer to our project page for more results.

We study the problem of 3D-aware full-body human generation, aiming at creating animatable human avatars with high-quality textures and geometries. Generally, two challenges remain in this field: i) existing methods struggle to generate geometries with rich realistic details such as the wrinkles of garments; ii) they typically utilize volumetric radiance fields and neural renderers in the synthesis process, making high-resolution rendering non-trivial. To overcome these problems, we propose GETAvatar, a Generative model that directly generates Explicit Textured 3D meshes for animatable human Avatar, with photorealistic appearance and fine geometric details. Specifically, we first design an articulated 3D human representation with explicit surface modeling, and enrich the generated humans with realistic surface details by learning from the 2D normal maps of 3D scan data. Second, with the explicit mesh representation, we can use a rasterization-based renderer to perform surface rendering, allowing us to achieve high-resolution image generation efficiently. Extensive experiments demonstrate that GETAvatar achieves state-of-the-art performance on 3D-aware human generation both in appearance and geometry quality. Notably, GETAvatar can generate images at 5122resolution with 17FPS and 10242resolution with 14FPS, improving upon previous methods by 2×. Our code and models will be at https://getavatar.github.io/.

Abstract This paper studies compositional 3D-aware image synthesis for both single-object and multi-object scenes. We observe that two challenges remain in this field: existing approaches (1) lack geometry constraints and thus compromise the multi-view consistency of the single object, and (2) can not scale to multi-object scenes with complex backgrounds. To address these challenges coherently, we propose multi-view consistent generative adversarial networks (MVCGAN) for compositional 3D-aware image synthesis. First, we build the geometry constraints on the single object by leveraging the underlying 3D information. Specifically, we enforce the photometric consistency between pairs of views, encouraging the model to learn the inherent 3D shape. Second, we adapt MVCGAN to multi-object scenarios. In particular, we formulate the multi-object scene generation as a “decompose and compose” process. During training, we adopt the top-down strategy to decompose training images into objects and backgrounds. When rendering, we deploy a reverse bottom-up manner by composing the generated objects and background into the holistic scene. Extensive experiments on both single-object and multi-object datasets show that the proposed method achieves competitive performance for 3D-aware image synthesis.

3D-aware image synthesis aims to generate images of objects from multiple views by learning a 3D representation. However, one key challenge remains: existing approaches lack geometry constraints, hence usually fail to generate multi-view consistent images. To address this challenge, we propose Multi-View Consistent Generative Adversarial Networks (MVCGAN) for high-quality 3D-aware image synthesis with geometry constraints. By leveraging the underlying 3D geometry information of generated images, i.e., depth and camera transformation matrix, we explicitly establish stereo correspondence between views to perform multi-view joint optimization. In particular, we enforce the photometric consistency between pairs of views and integrate a stereo mixup mechanism into the training process, encouraging the model to reason about the correct 3D shape. Besides, we design a two-stage training strategy with feature-level multi-view joint optimization to improve the image quality. Extensive experiments on three datasets demonstrate that MVCGAN achieves the state-of-the-art performance for 3D-aware image synthesis.