GenAI4ELab/papercli-papers huggingface dataset:
Scaffold-GS: Structured 3D Gaussians for View-Adaptive Rendering
Authors: Tao Lu; Mulin Yu; Linning Xu; Yuanbo Xiangli; Limin Wang; Dahua Lin; Bo Dai
Venue: CVPR 2024 (main)

Abstract: Neural rendering methods have significantly advanced photo-realistic 3D scene rendering in various academic and industrial applications. The recent 3D Gaussian Splatting method has achieved the state-of-the-art rendering quality and speed combining the benefits of both primitive-based representations and volumetric representations. However it often leads to heavily redundant Gaussians that try to fit every training view neglecting the underlying scene geometry. Consequently the resulting model becomes less robust to significant view changes texture-less area and lighting effects. We introduce Scaffold-GS which uses anchor points to distribute local 3D Gaussians and predicts their attributes on-the-fly based on viewing direction and distance within the view frustum. Anchor growing and pruning strategies are developed based on the importance of neural Gaussians to reliably improve the scene coverage. We show that our method effectively reduces redundant Gaussians while delivering high-quality rendering. We also demonstrates an enhanced capability to accommodate scenes with varying levels-of-detail and view-dependent observations without sacrificing the rendering speed. Project page: https://city-super.github.io/scaffold-gs.
Data Valuation and Detections in Federated Learning
Authors: Wenqian Li; Shuran Fu; Fengrui Zhang; Yan Pang
Venue: CVPR 2024 (main)

Abstract: Federated Learning (FL) enables collaborative model training while preserving the privacy of raw data. A challenge in this framework is the fair and efficient valuation of data which is crucial for incentivizing clients to contribute high-quality data in the FL task. In scenarios involving numerous data clients within FL it is often the case that only a subset of clients and datasets are pertinent to a specific learning task while others might have either a negative or negligible impact on the model training process. This paper introduces a novel privacy-preserving method for evaluating client contributions and selecting relevant datasets without a pre-specified training algorithm in an FL task. Our proposed approach \texttt FedBary  utilizes Wasserstein distance within the federated context offering a new solution for data valuation in the FL framework. This method ensures transparent data valuation and efficient computation of the Wasserstein barycenter and reduces the dependence on validation datasets. Through extensive empirical experiments and theoretical analyses we demonstrate the advantages of this data valuation method as a promising avenue for FL research.
Classes Are Not Equal: An Empirical Study on Image Recognition Fairness
Authors: Jiequan Cui; Beier Zhu; Xin Wen; Xiaojuan Qi; Bei Yu; Hanwang Zhang
Venue: CVPR 2024 (main)

Abstract: In this paper we present an empirical study on image recognition unfairness i.e. extreme class accuracy disparity on balanced data like ImageNet. We demonstrate that classes are not equal and unfairness is prevalent for image classification models across various datasets network architectures and model capacities. Moreover several intriguing properties of fairness are identified. First the unfairness lies in problematic representation rather than classifier bias distinguished from long-tailed recognition. Second with the proposed concept of Model Prediction Bias we investigate the origins of problematic representation during training optimization. Our findings reveal that models tend to exhibit greater prediction biases for classes that are more challenging to recognize. It means that more other classes will be confused with harder classes. Then the False Positives (FPs) will dominate the learning in optimization thus leading to their poor accuracy. Further we conclude that data augmentation and representation learning algorithms improve overall performance by promoting fairness to some degree in image classification.
Human Gaussian Splatting: Real-time Rendering of Animatable Avatars
Authors: Arthur Moreau; Jifei Song; Helisa Dhamo; Richard Shaw; Yiren Zhou; Eduardo Pérez-Pellitero
Venue: CVPR 2024 (main)

Abstract: This work addresses the problem of real-time rendering of photorealistic human body avatars learned from multi-view videos. While the classical approaches to model and render virtual humans generally use a textured mesh recent research has developed neural body representations that achieve impressive visual quality. However these models are difficult to render in real-time and their quality degrades when the character is animated with body poses different than the training observations. We propose an animatable human model based on 3D Gaussian Splatting that has recently emerged as a very efficient alternative to neural radiance fields. The body is represented by a set of gaussian primitives in a canonical space which is deformed with a coarse to fine approach that combines forward skinning and local non-rigid refinement. We describe how to learn our Human Gaussian Splatting (HuGS) model in an end-to-end fashion from multi-view observations and evaluate it against the state-of-the-art approaches for novel pose synthesis of clothed body. Our method achieves 1.5 dB PSNR improvement over the state-of-the-art on THuman4 dataset while being able to render in real-time (?80 fps for 512x512 resolution).
Multi-Scale 3D Gaussian Splatting for Anti-Aliased Rendering
Authors: Zhiwen Yan; Weng Fei Low; Yu Chen; Gim Hee Lee
Venue: CVPR 2024 (main)

Abstract: 3D Gaussians have recently emerged as a highly efficient representation for 3D reconstruction and rendering. Despite its high rendering quality and speed at high resolutions they both deteriorate drastically when rendered at lower resolutions or from far away camera position. During low resolution or far away rendering the pixel size of the image can fall below the Nyquist frequency compared to the screen size of each splatted 3D Gaussian and leads to aliasing effect. The rendering is also drastically slowed down by the sequential alpha blending of more splatted Gaussians per pixel. To address these issues we propose a multi-scale 3D Gaussian splatting algorithm which maintains Gaussians at different scales to represent the same scene. Higher-resolution images are rendered with more small Gaussians and lower-resolution images are rendered with fewer larger Gaussians. With similar training time our algorithm can achieve 13%-66% PSNR and 160%-2400% rendering speed improvement at 4x-128x scale rendering on Mip-NeRF360 dataset compared to the single scale 3D Gaussian splatting.
A Bayesian Approach to OOD Robustness in Image Classification
Authors: Prakhar Kaushik; Adam Kortylewski; Alan Yuille
Venue: CVPR 2024 (main)

Abstract: An important and unsolved problem in computer vision is to ensure that the algorithms are robust to changes in image domains. We address this problem in the scenario where we have access to images from the target domains but no annotations. Motivated by the challenges of the OOD-CV benchmark where we encounter real world Out-of-Domain (OOD) nuisances and occlusion we introduce a novel Bayesian approach to OOD robustness for object classification. Our work extends Compositional Neural Networks (CompNets) which have been shown to be robust to occlusion but degrade badly when tested on OOD data. We exploit the fact that CompNets contain a generative head defined over feature vectors represented by von Mises-Fisher (vMF) kernels which correspond roughly to object parts and can be learned without supervision. We obverse that some vMF kernels are similar between different domains while others are not. This enables us to learn a transitional dictionary of vMF kernels that are intermediate between the source and target domains and train the generative model on this dictionary using the annotations on the source domain followed by iterative refinement. This approach termed Unsupervised Generative Transition (UGT) performs very well in OOD scenarios even when occlusion is present. UGT is evaluated on different OOD benchmarks including the OOD-CV dataset several popular datasets (e.g. ImageNet-C artificial image corruptions (including adding occluders) and synthetic-to-real domain transfer and does well in all scenarios outperforming SOTA alternatives.
Unified-IO 2: Scaling Autoregressive Multimodal Models with Vision Language Audio and Action
Authors: Jiasen Lu; Christopher Clark; Sangho Lee; Zichen Zhang; Savya Khosla; Ryan Marten; Derek Hoiem; Aniruddha Kembhavi
Venue: CVPR 2024 (main)

Abstract: We present Unified-IO 2 a multimodal and multi-skill unified model capable of following novel instructions. Unified-IO 2 can use text images audio and/or videos as input and can generate text image or audio outputs which is accomplished in a unified way by tokenizing these different inputs and outputs into a shared semantic space that can then be processed by a single encoder-decoder transformer model. Unified-IO 2 is trained from scratch on a custom-built multimodal pre-training corpus and then learns an expansive set of skills through fine-tuning on over 120 datasets including datasets for segmentation object detection image editing audio localization video tracking embodied AI and 3D detection. To facilitate instruction-following we add prompts and other data augmentations to these tasks to allow Unified-IO 2 to generalize these skills to new tasks zero-shot. Unified-IO 2 is the first model to be trained on such a diverse and wide-reaching set of skills and unify three separate generation capabilities. Unified-IO 2 achieves state-of-the-art performance on the multi-task GRIT benchmark and achieves strong results on 30 diverse datasets including SEED-Bench image and video understanding TIFA image generation VQA 2.0 ScienceQA VIMA robotic manipulation VGG-Sound and Kinetics-Sounds and can perform unseen tasks and generate free-form responses. We release our model and code to facilitate future work.
Joint Reconstruction of 3D Human and Object via Contact-Based Refinement Transformer
Authors: Hyeongjin Nam; Daniel Sungho Jung; Gyeongsik Moon; Kyoung Mu Lee
Venue: CVPR 2024 (main)

Abstract: Human-object contact serves as a strong cue to understand how humans physically interact with objects. Nevertheless it is not widely explored to utilize human-object contact information for the joint reconstruction of 3D human and object from a single image. In this work we present a novel joint 3D human-object reconstruction method (CONTHO) that effectively exploits contact information between humans and objects. There are two core designs in our system: 1) 3D-guided contact estimation and 2) contact-based 3D human and object refinement. First for accurate human-object contact estimation CONTHO initially reconstructs 3D humans and objects and utilizes them as explicit 3D guidance for contact estimation. Second to refine the initial reconstructions of 3D human and object we propose a novel contact-based refinement Transformer that effectively aggregates human features and object features based on the estimated human-object contact. The proposed contact-based refinement prevents the learning of erroneous correlation between human and object which enables accurate 3D reconstruction. As a result our CONTHO achieves state-of-the-art performance in both human-object contact estimation and joint reconstruction of 3D human and object. The codes are available in https://github.com/dqj5182/CONTHO_RELEASE.
TIM: A Time Interval Machine for Audio-Visual Action Recognition
Authors: Jacob Chalk; Jaesung Huh; Evangelos Kazakos; Andrew Zisserman; Dima Damen
Venue: CVPR 2024 (main)

Abstract: Diverse actions give rise to rich audio-visual signals in long videos. Recent works showcase that the two modalities of audio and video exhibit different temporal extents of events and distinct labels. We address the interplay between the two modalities in long videos by explicitly modelling the temporal extents of audio and visual events. We propose the Time Interval Machine (TIM) where a modality-specific time interval poses as a query to a transformer encoder that ingests a long video input. The encoder then attends to the specified interval as well as the surrounding context in both modalities in order to recognise the ongoing action. We test TIM on three long audio-visual video datasets: EPIC-KITCHENS Perception Test and AVE reporting state-of-the-art (SOTA) for recognition. On EPIC-KITCHENS we beat previous SOTA that utilises LLMs and significantly larger pre-training by 2.9% top-1 action recognition accuracy. Additionally we show that TIM can be adapted for action detection using dense multi-scale interval queries outperforming SOTA on EPIC-KITCHENS-100 for most metrics and showing strong performance on the Perception Test. Our ablations show the critical role of integrating the two modalities and modelling their time intervals in achieving this performance. Code and models at: https://github.com/JacobChalk/TIM.
The Devil is in the Details: StyleFeatureEditor for Detail-Rich StyleGAN Inversion and High Quality Image Editing
Authors: Denis Bobkov; Vadim Titov; Aibek Alanov; Dmitry Vetrov
Venue: CVPR 2024 (main)

Abstract: The task of manipulating real image attributes through StyleGAN inversion has been extensively researched. This process involves searching latent variables from a well-trained StyleGAN generator that can synthesize a real image modifying these latent variables and then synthesizing an image with the desired edits. A balance must be struck between the quality of the reconstruction and the ability to edit. Earlier studies utilized the low-dimensional W-space for latent search which facilitated effective editing but struggled with reconstructing intricate details. More recent research has turned to the high-dimensional feature space F which successfully inverses the input image but loses much of the detail during editing. In this paper we introduce StyleFeatureEditor -- a novel method that enables editing in both w-latents and F-latents. This technique not only allows for the reconstruction of finer image details but also ensures their preservation during editing. We also present a new training pipeline specifically designed to train our model to accurately edit F-latents. Our method is compared with state-of-the-art encoding approaches demonstrating that our model excels in terms of reconstruction quality and is capable of editing even challenging out-of-domain examples.
Unbiased Estimator for Distorted Conics in Camera Calibration
Authors: Chaehyeon Song; Jaeho Shin; Myung-Hwan Jeon; Jongwoo Lim; Ayoung Kim
Venue: CVPR 2024 (main)

Abstract: In the literature points and conics have been major features for camera geometric calibration. Although conics are more informative features than points the loss of the conic property under distortion has critically limited the utility of conic features in camera calibration. Many existing approaches addressed conic-based calibration by ignoring distortion or introducing 3D spherical targets to circumvent this limitation. In this paper we present a novel formulation for conic-based calibration using moments. Our derivation is based on the mathematical finding that the first moment can be estimated without bias even under distortion. This allows us to track moment changes during projection and distortion ensuring the preservation of the first moment of the distorted conic. With an unbiased estimator the circular patterns can be accurately detected at the sub-pixel level and can now be fully exploited for an entire calibration pipeline resulting in significantly improved calibration. The entire code is readily available from https://github.com/ChaehyeonSong/discocal.
MultiPhys: Multi-Person Physics-aware 3D Motion Estimation
Authors: Nicolas Ugrinovic; Boxiao Pan; Georgios Pavlakos; Despoina Paschalidou; Bokui Shen; Jordi Sanchez-Riera; Francesc Moreno-Noguer; Leonidas Guibas
Venue: CVPR 2024 (main)

Abstract: We introduce MultiPhys a method designed for recovering multi-person motion from monocular videos. Our focus lies in capturing coherent spatial placement between pairs of individuals across varying degrees of engagement. MultiPhys being physically aware exhibits robustness to jittering and occlusions and effectively eliminates penetration issues between the two individuals. We devise a pipeline in which the motion estimated by a kinematic-based method is fed into a physics simulator in an autoregressive manner. We introduce distinct components that enable our model to harness the simulator's properties without compromising the accuracy of the kinematic estimates. This results in final motion estimates that are both kinematically coherent and physically compliant. Extensive evaluations on three challenging datasets characterized by substantial inter-person interaction show that our method significantly reduces errors associated with penetration and foot skating while performing competitively with the state-of-the-art on motion accuracy and smoothness.
Multi-Level Neural Scene Graphs for Dynamic Urban Environments
Authors: Tobias Fischer; Lorenzo Porzi; Samuel Rota Bulo; Marc Pollefeys; Peter Kontschieder
Venue: CVPR 2024 (main)

Abstract: We estimate the radiance field of large-scale dynamic areas from multiple vehicle captures under varying environmental conditions. Previous works in this domain are either restricted to static environments do not scale to more than a single short video or struggle to separately represent dynamic object instances. To this end we present a novel decomposable radiance field approach for dynamic urban environments. We propose a multi-level neural scene graph representation that scales to thousands of images from dozens of sequences with hundreds of fast-moving objects. To enable efficient training and rendering of our representation we develop a fast composite ray sampling and rendering scheme. To test our approach in urban driving scenarios we introduce a new novel view synthesis benchmark. We show that our approach outperforms prior art by a significant margin on both established and our proposed benchmark while being faster in training and rendering.
Would Deep Generative Models Amplify Bias in Future Models?
Authors: Tianwei Chen; Yusuke Hirota; Mayu Otani; Noa Garcia; Yuta Nakashima
Venue: CVPR 2024 (main)

Abstract: We investigate the impact of deep generative models on potential social biases in upcoming computer vision models. As the internet witnesses an increasing influx of AI-generated images concerns arise regarding inherent biases that may accompany them potentially leading to the dissemination of harmful content. This paper explores whether a detrimental feedback loop resulting in bias amplification would occur if generated images were used as the training data for future models. We conduct simulations by progressively substituting original images in COCO and CC3M datasets with images generated through Stable Diffusion. The modified datasets are used to train OpenCLIP and image captioning models which we evaluate in terms of quality and bias. Contrary to expectations our findings indicate that introducing generated images during training does not uniformly amplify bias. Instead instances of bias mitigation across specific tasks are observed. We further explore the factors that may influence these phenomena such as artifacts in image generation (e.g. blurry faces) or pre-existing biases in the original datasets.
Bayes' Rays: Uncertainty Quantification for Neural Radiance Fields
Authors: Lily Goli; Cody Reading; Silvia Sellán; Alec Jacobson; Andrea Tagliasacchi
Venue: CVPR 2024 (main)

Abstract: Neural Radiance Fields (NeRFs) have shown promise in applications like view synthesis and depth estimation but learning from multiview images faces inherent uncertainties. Current methods to quantify them are either heuristic or computationally demanding. We introduce BayesRays a post-hoc framework to evaluate uncertainty in any pretrained NeRF without modifying the training process. Our method establishes a volumetric uncertainty field using spatial perturbations and a Bayesian Laplace approximation. We derive our algorithm statistically and show its superior performance in key metrics and applications. Additional results available at: https://bayesrays.github.io/
NIVeL: Neural Implicit Vector Layers for Text-to-Vector Generation
Authors: Vikas Thamizharasan; Difan Liu; Matthew Fisher; Nanxuan Zhao; Evangelos Kalogerakis; Michal Lukac
Venue: CVPR 2024 (main)

Abstract: The success of denoising diffusion models in representing rich data distributions over 2D raster images has prompted research on extending them to other data representations such as vector graphics. Unfortunately due to their variable structure and scarcity of vector training data directly applying diffusion models on this domain remains a challenging problem. Using workarounds like optimization via Score Distillation Sampling (SDS) is also fraught with difficulty as vector representations are non-trivial to directly optimize and tend to result in implausible geometries such as redundant or self-intersecting shapes. NIVeL addresses these challenges by reinterpreting the problem on an alternative intermediate domain which preserves the desirable properties of vector graphics - mainly sparsity of representation and resolution-independence. This alternative domain is based on neural implicit fields expressed in a set of decomposable editable layers. Based on our experiments NIVeL produces text-to-vector graphics results of significantly better quality than the state-of-the-art.
Driving-Video Dehazing with Non-Aligned Regularization for Safety Assistance
Authors: Junkai Fan; Jiangwei Weng; Kun Wang; Yijun Yang; Jianjun Qian; Jun Li; Jian Yang
Venue: CVPR 2024 (main)

Abstract: Real driving-video dehazing poses a significant challenge due to the inherent difficulty in acquiring precisely aligned hazy/clear video pairs for effective model training especially in dynamic driving scenarios with unpredictable weather conditions. In this paper we propose a pioneering approach that addresses this challenge through a nonaligned regularization strategy. Our core concept involves identifying clear frames that closely match hazy frames serving as references to supervise a video dehazing network. Our approach comprises two key components: reference matching and video dehazing. Firstly we introduce a non-aligned reference frame matching module leveraging an adaptive sliding window to match high-quality reference frames from clear videos. Video dehazing incorporates flow-guided cosine attention sampler and deformable cosine attention fusion modules to enhance spatial multiframe alignment and fuse their improved information. To validate our approach we collect a GoProHazy dataset captured effortlessly with GoPro cameras in diverse rural and urban road environments. Extensive experiments demonstrate the superiority of the proposed method over current state-of-the-art methods in the challenging task of real driving-video dehazing. Project page.