ECCV 2024 Papers

"Novel view synthesis has achieved remarkable quality and efficiency by the paradigm of 3D Gaussian Splatting (3D-GS), but still faces two challenges: 1) significant performance degradation when trained with only few-shot samples due to a lack of geometry constraint, and 2) incapability of rendering at a higher resolution that is beyond the input resolution of training samples. In this paper, we propose Dual-Lens 3D-GS (DL-GS) to achieve high-resolution (HR) and few-shot view synthesis, by leveraging the characteristics of the asymmetric dual-lens system commonly equipped on mobile devices. This kind of system captures the same scene with different focal lengths (i.e., wide-angle and telephoto) under an asymmetric stereo configuration, which naturally provides geometric hints for few-shot training and HR guidance for resolution improvement. Nevertheless, there remain two major technical problems to achieving this goal. First, how to effectively exploit the geometry information from the asymmetric stereo configuration? To this end, we propose a consistency-aware training strategy, which integrates a dual-lens-consistent loss to regularize the 3D-GS optimization. Second, how to make the best use of the dual-lens training samples to effectively improve the resolution of newly synthesized views? To this end, we design a multi-reference-guided refinement module to select proper telephoto and wide-angle guided images from training samples based on the camera pose distances, and then exploit their information for high-frequency detail enhancement. Extensive experiments on simulated and real-captured datasets validate the distinct superiority of our DL-GS over various competitors on the task of HR and few-shot view synthesis. The implementation code is available at https://github.com/XrKang/ DL-GS."

"Mesh-based facial blendshapes have been widely used in animation pipelines, while recent advancements in neural geometry and appearance representations have enabled high-quality inverse rendering. Building upon these observations, we introduce a novel technique that reconstructs mesh-based blendshape rigs from single or sparse multi-view videos, leveraging state-of-the-art neural inverse rendering. We begin by constructing a deformation representation that parameterizes vertex displacements into differential coordinates with tetrahedral connections, allowing for high-quality vertex deformation on high-resolution meshes. By constructing a set of semantic regulations in this representation, we achieve joint optimization of blendshapes and expression coefficients. Furthermore, to enable a user-friendly multi-view setup with unsynchronized cameras, we use a neural regressor to model time-varying motion parameters. Experiments demonstrate that, with the flexible input of single or sparse multi-view videos, we reconstruct personalized high-fidelity blendshapes. These blendshapes are both geometrically and semantically accurate, and they are compatible with industrial animation pipelines. Code and data are available at https://github. com/grignarder/high-quality-blendshape-generation."

"In the area of self-supervised monocular depth estimation, models that utilize rich-resource inputs, such as high-resolution and multi-frame inputs, typically achieve better performance than models that use ordinary single image input. However, these rich-resource inputs may not always be available, limiting the applicability of these methods in general scenarios. In this paper, we propose Rich-resource Prior Depth estimator (RPrDepth), which only requires single input image during the inference phase but can still produce highly accurate depth estimations comparable to rich-resource based methods. Specifically, we treat rich-resource data as prior information and extract features from it as reference features in an offline manner. When estimating the depth for a single-image image, we search for similar pixels from the rich-resource features and use them as prior information to estimate the depth. Experimental results demonstrate that our model outperform other single-image model and can achieve comparable or even better performance than models with rich-resource inputs, only using low-resolution single-image input."

"This paper enables high-fidelity, transferable NeRF editing by frequency decomposition. Recent NeRF editing pipelines lift 2D stylization results to 3D scenes while suffering from blurry results, and fail to capture detailed structures caused by the inconsistency between 2D editings. Our critical insight is that low-frequency components of images are more multiview-consistent after editing compared with their high-frequency parts. Moreover, the appearance style is mainly exhibited on the low-frequency components, and the content details especially reside in high-frequency parts. This motivates us to perform editing on low-frequency components, which results in high-fidelity edited scenes. In addition, the editing is performed in the low-frequency feature space, enabling stable intensity control and novel scene transfer. Comprehensive experiments conducted on photorealistic datasets demonstrate the superior performance of high-fidelity and transferable NeRF editing. The project page is at https: //aigc3d.github.io/freditor."

"This paper proposes a generalizable model to synthesize high-fidelity clothing wrinkle deformation in 3D by learning from real data. Given the complex deformation behaviors of real-world clothing, this task presents significant challenges, primarily due to the lack of accurate ground-truth data. Obtaining high-fidelity 3D deformations requires special equipment like a multi-camera system, which is not easily scalable. To address this challenge, we decompose the clothing into a base surface and fine wrinkles; and introduce a new method that can generate wrinkles as high-frequency 3D displacement from coarse clothing deformation. Our method is conditioned by Green-Lagrange strain field—a local rotation-invariant measurement that is independent of body and clothing topology, enhancing its generalizability. Using limited real data (e.g., 3K) of garment meshes, we train a diffusion model that can generate high-fidelity wrinkles from a coarse clothing mesh, conditioned on its strain field. Practically, we obtain the coarse clothing mesh using a body-conditioned VAE, ensuring compatibility of the deformation with the body pose. In our experiments, we demonstrate that our generative wrinkle model outperforms existing methods by synthesizing high-fidelity wrinkle deformation from novel body poses and clothing while preserving the quality comparable to the one from training data."

"3D vision is inherently characterized by sparse spatial structures, which propels the necessity for an efficient paradigm tailored to 3D generation. Another discrepancy is the amount of training data, which undeniably affects generalization if we only use limited 3D data. To solve these, we design a 3D generation framework that maintains most of the building blocks of StableDiffusion with minimal adaptations for textured shape generation. We design a Sparse Encoding Module for details preservation and an Adversarial Decoding Module for better shape recovery. Moreover, we clean up data and build a benchmark on the biggest 3D dataset (Objaverse). We drop the concept of ‘specific class’ and treat the 3D Textured Shapes Generation as an open-vocabulary problem. We first validate our network design on ShapeNetV2 with 55K samples on single-class unconditional generation and multi-class conditional generation tasks. Then we report metrics on processed G-Objaverse with 200K samples on the image conditional generation task. Extensive experiments demonstrate our proposal outperforms SOTA methods and takes a further step towards open-vocabulary 3D generation. We release the processed data at https://aigc3d.github.io/gobjaverse/."

"We propose a new framework for creating and easily manipulating 3D models of arbitrary objects using casually captured videos. Our core ingredient is a novel hierarchy deformation model, which captures motions of objects with a tree-structured bones. Our hierarchy system decomposes motions based on the granularity and reveals the correlations between parts without exploiting any prior structural knowledge. We further propose to regularize the bones to be positioned at the basis of motions, centers of parts, sufficiently covering related surfaces of the part. This is achieved by our bone occupancy function, which identifies whether a given 3D point is placed within the bone. Coupling the proposed components, our framework offers several clear advantages: (1) Users can obtain animatable 3D models of the arbitrary objects in improved quality from their casual videos, (2) users can manipulate 3D models in an intuitive manner with minimal costs, and (3) users can interactively add or delete control points as necessary. The experimental results demonstrate the efficacy of our framework on diverse instances, in reconstruction quality, interpretability and easier manipulation. Our code is available at https://github.com/subin6/ HSNB."

"Source free domain adaptation (SFDA) aims to transfer the model trained on labeled source domain to unlabeled target domain without accessing source data. Recent SFDA methods predominantly rely on self-training, which supervise the model with pseudo labels generated from individual data samples. However, they often ignore the crucial data structure information and sample relationships that are beneficial for adaptive training. In this paper, we propose a novel hierarchical relation distillation framework, establishing multi-level relations across samples in an unsupervised manner, which fully exploits inherent data structure to guide sample training instead of using isolated pseudo labels. We first distinguish source-like samples based on prediction reliability during training, followed by an effort on distilling knowledge to those target-specific ones by transferring both local clustering relation and global semantic relation. Specifically, we leverage the affinity with nearest neighborhood samples for local relation and consider the similarity to category-wise Gaussian Mixtures for global relation, offering complementary supervision to facilitate student learning. To validate our approach’s effectiveness, we conduct extensive experiments on diverse benchmarks, achieving better performance compared to previous methods."

"Camera-based 3D semantic scene completion (SSC) is pivotal for predicting complicated 3D layouts with limited 2D image observations. The existing mainstream solutions generally leverage temporal information by roughly stacking history frames to supplement the current frame, such straightforward temporal modeling inevitably diminishes valid clues and increases learning difficulty. To address this problem, we present HTCL, a novel Hierarchical Temporal Context Learning paradigm for improving camera-based semantic scene completion. The primary innovation of this work involves decomposing temporal context learning into two hierarchical steps: (a) cross-frame affinity measurement and (b) affinity-based dynamic refinement. Firstly, to separate critical relevant context from redundant information, we introduce the pattern affinity with scale-aware isolation and multiple independent learners for fine-grained contextual correspondence modeling. Subsequently, to dynamically compensate for incomplete observations, we adaptively refine the feature sampling locations based on initially identified locations with high affinity and their neighboring relevant regions. Our method ranks 1st on the SemanticKITTI benchmark and even surpasses LiDAR-based methods in terms of mIoU on the OpenOccupancy benchmark. Our code is available on https://github.com/Arlo0o/HTCL."

"Transformers have achieved the state-of-the-art performance on solving the inverse problem of Snapshot Compressive Imaging (SCI) for video, whose ill-posedness is rooted in the mixed degradation of spatial masking and temporal aliasing. However, previous Transformers lack an insight into the degradation and thus have limited performance and efficiency. In this work, we tailor an efficient reconstruction architecture without temporal aggregation in early layers and Hierarchical Separable Video Transformer (HiSViT) as building block. HiSViT is built by multiple groups of Cross-Scale Separable Multi-head Self-Attention (CSS-MSA) and Gated Self-Modulated Feed-Forward Network (GSM-FFN) with dense connections, each of which is conducted within a separate channel portions at a different scale, for multi-scale interactions and long-range modeling. By separating spatial operations from temporal ones, CSS-MSA introduces an inductive bias of paying more attention within frames instead of between frames while saving computational overheads. GSM-FFN further enhances the locality via gated mechanism and factorized spatial-temporal convolutions. Extensive experiments demonstrate that our method outperforms previous methods by > 0.5 dB with comparable or fewer parameters and complexity. The source codes and pretrained models are released at https://github.com/pwangcs/HiSViT."

"Unified anomaly detection (AD) is one of the most valuable challenges for anomaly detection, where one unified model is trained with normal samples from multiple classes with the objective to detect anomalies in these classes. For such a challenging task, popular normalizing flow (NF) based AD methods may fall into a “homogeneous mapping” issue, where the NF-based AD models are biased to generate similar latent representations for both normal and abnormal features, and thereby lead to a high missing rate of anomalies. In this paper, we propose a novel Hierarchical Gaussian mixture normalizing flow modeling method for accomplishing unified Anomaly Detection, which we call HGAD. Our HGAD consists of two key components: inter-class Gaussian mixture modeling and intra-class mixed class centers learning. Compared to the previous NF-based AD methods, the hierarchical Gaussian mixture modeling approach can bring stronger representation capability to the latent space of normalizing flows. In this way, we can avoid mapping different class distributions into the same single Gaussian prior, thus effectively avoiding or mitigating the “homogeneous mapping” issue. We further indicate that the more distinguishable different class centers, the more conducive to avoiding the bias issue. Thus, we further propose a mutual information maximization loss for better structuring the latent feature space. We evaluate our method on four real-world AD benchmarks, where we can significantly improve the previous NF-based AD methods and also outperform the SOTA unified AD methods. The code will be available at https://github.com/xcyao00/HGAD."

"A central problem in biology is to understand how organisms evolve and adapt to their environment by acquiring variations in the observable characteristics or traits of species across the tree of life. With the growing availability of large-scale image repositories in biology and recent advances in generative modeling, there is an opportunity to accelerate the discovery of evolutionary traits automatically from images. Toward this goal, we introduce Phylo-Diffusion, a novel framework for conditioning diffusion models with phylogenetic knowledge represented in the form of HIERarchical Embeddings (HIER-Embeds). We also propose two new experiments for perturbing the embedding space of Phylo-Diffusion: trait masking and trait swapping, inspired by counterpart experiments of gene knockout and gene editing/swapping. Our work represents a novel methodological advance in generative modeling to structure the embedding space of diffusion models using tree-based knowledge. Our work also opens a new chapter of research in evolutionary biology by using generative models to visualize evolutionary changes directly from images. We empirically demonstrate the usefulness of Phylo-Diffusion in capturing meaningful trait variations for fishes and birds, revealing novel insights about the biological mechanisms of their evolution. 1 1 Model and code can be found at imageomics.github.io/phylo-diffusion"

"With the maturity of depth sensors, point clouds have received increasing attention in various 3D safety-critical applications, while deep point cloud learning models have been shown to be vulnerable to adversarial attacks. Most existing 3D attackers rely on implicit global distance losses to perturb whole points, failing to restrict the proper 3D geometry as point clouds are highly structured. To this end, in this paper, we propose a novel Wavelet Patches Attack (WPA), which leverages local spectral attributes to identify curvature-aware patches for hiding imperceptible perturbations aligned with their local geometric characteristics. Specifically, WPA first transforms the point cloud into the spectral domain using a wavelet operator, obtaining potential geometric structures in different local regions. Each wavelet corresponds to different curvature contexts of local points. Then, by decomposing the 3D object with different curvature-aware levels through the wavelet coefficients, we can perceive the local geometric characteristics and get various curvature-consistent patches. At last, based on the curvature variations of patches, WPA introduces two-type perturbations along the tangent plane and normal vector direction to hide imperceptible noise in slow- and fast-variation patches for preserving the geometric-sensitive local characteristics of smoothness and sharpness, respectively. Experiments demonstrate the superior imperceptibility of our attack method, achieving favorable results on existing 3D classification models while exhibiting robust resistance to various defense mechanisms."

"With the advancements of vision-language models, the growing demand for generating customized image descriptions under length, target regions, and other various control conditions brings new challenges for evaluation. Most existing metrics, designed primarily for single-sentence image captioning with an overall matching score, struggle to accommodate complex description requirements, resulting in insufficient accuracy and interpretability of evaluation. Therefore, we propose HiFi-Score, a hierarchical parsing graph-based fine-grained evaluation metric. Specifically, we model both text and images as parsing graphs, which organize multi-granular instances into a hierarchical structure according to their inclusion relationships, which provides a comprehensive scene analysis for both modalities from global to local. Based on the fine-grained matching between the graphs, we can evaluate the fidelity to ensure text contents are related to image and the adequacy to ensure the image is covered by text at multiple levels. Furthermore, we employ the large language model to evaluate fluency of the language expression. Human correlation experiments on four caption-level benchmarks show that the proposed metric outperforms existing metrics. At the paragraph-level, we construct a novel dataset ParaEval and demonstrate the accuracy of the HiFi-Score in evaluating long texts. We further show its superiority in assessing vision-language models and its flexibility when applied to various image description tasks."

"Recent advances in diffusion models have enabled 3D generation from a single image. However, current methods often produce suboptimal results for novel views, with blurred textures and deviations from the reference image, limiting their practical applications. In this paper, we introduce HiFi-123, a method designed for high-fidelity and multi-view consistent 3D generation. Our contributions are twofold: First, we propose a Reference-Guided Novel View Enhancement (RGNV) technique that significantly improves the fidelity of diffusion-based zero-shot novel view synthesis methods. Second, capitalizing on the RGNV, we present a novel Reference-Guided State Distillation (RGSD) loss. When incorporated into the optimization-based image-to-3D pipeline, our method significantly improves 3D generation quality, achieving state-of-the-art performance. Comprehensive evaluations demonstrate the effectiveness of our approach over existing methods, both qualitatively and quantitatively. Video results are available on the project page."

"Emerging images (EIs) are a type of stylized image that consists of discrete speckles with irregular shapes and sizes, colored only in black and white. EIs have significant applications that can contribute to the study of perceptual organization in cognitive psychology and serve as a CAPTCHA mechanism. However, generating high-quality EIs from natural images faces the following challenges: 1) color quantization–how to minimize perceptual loss when reducing the color space of a natural image to 1-bit; 2) perceived difficulty adjustment–how to adjust the perceived difficulty for object detection and recognition. This paper proposes a universal framework HiEI to generate high-quality EIs from natural images, which contains three modules: the human-centered color quantification module (TTNet), the perceived difficulty control (PDC) module, and the template vectorization (TV) module. TTNet and PDC modules are specifically designed to address the aforementioned challenges. Experimental results show that compared to the existing EI generation methods, HiEI can generate EIs with superior content and style quality while offering more flexibility in controlling perceived difficulty. In particular, we experimently demonstrate that EIs generated by HiEI can effectively defend against attacks from deep network-based visual models, confirming their viability as a CAPTCHA mechanism."

"Diffusion models have become a mainstream approach for high-resolution image synthesis. However, directly generating higher-resolution images from pretrained diffusion models will encounter unreasonable object duplication and exponentially increase the generation time. In this paper, we discover that object duplication arises from feature duplication in the deep blocks of the U-Net. Concurrently, We pinpoint the extended generation times to self-attention redundancy in U-Net’s top blocks. To address these issues, we propose a tuning-free higher-resolution framework named HiDiffusion. Specifically, HiDiffusion contains Resolution-Aware U-Net (RAU-Net) that dynamically adjusts the feature map size to resolve object duplication and engages Modified Shifted Window Multi-head Self-Attention (MSW-MSA) that utilizes optimized window attention to reduce computations. we can integrate HiDiffusion into various pretrained diffusion models to scale image generation resolutions even to 4096×4096 at 1.5-6× the inference speed of previous methods. Extensive experiments demonstrate that our approach can address object duplication and heavy computation issues, achieving state-of-the-art performance on higher-resolution image synthesis tasks."

"3D Scene Graph Prediction (SGP) aims to recognize the objects and predict their semantic and spatial relationships in a 3D scene. Existing methods either exploit context information or emphasize knowledge prior to model the scene graph in a fully-connected homogeneous graph framework. However, these methods may lead to indiscriminate message passing among graph nodes (i.e., objects), resulting in sub-optimal performance. In this paper, we propose a 3D Heterogeneous Scene Graph Prediction (3D-HetSGP) framework, which performs graph reasoning on the 3D scene graph in a heterogeneous fashion. Specifically, our method consists of two stages: a heterogeneous graph structure learning (HGSL) stage and a heterogeneous graph reasoning (HGR) stage. In the HGSL stage, we learn the graph structure by predicting the types of different directed edges. In the HGR stage, message passing among nodes is performed on the learned graph structure for scene graph prediction. Extensive experiments show that our method achieves comparable or superior performance to existing methods on 3DSSG dataset."

"Collaborative perception effectively expands the perception range of agents by sharing perceptual information, and it addresses the occlusion problem in single-vehicle perception. Most of the existing works are based on the assumption of perception model homogeneity. However, in actual collaboration scenarios, agents use different perception model architectures, which leads to differences in the size, number of channels and semantic space of intermediate features shared among collaborators, bringing challenges to collaboration. We introduce Hetecooper, a collaborative perception framework for scenarios with heterogeneous perception models. To model the correlation between heterogeneous features, we construct the feature collaboration graph, which completely preserves the semantic information and spatial information of features. Furthermore, a message passing mechanism based on graph transformer is designed to transfer feature messages in the feature collaboration graph. Firstly, the number of node channels and the semantic space are unified by the semantic mapper. Then, the feature information is aggregated by the edge weight guided attention, and finally the fusion of heterogeneous features is realized. Test results demonstrate that our method achieves superior performance in both model homogeneity and heterogeneity scenarios, and also has good scalability to the change of feature size."