CVPR 2024 Papers

Event cameras with their high temporal and dynamic range and minimal memory usage have found applications in various fields. However their potential in static traffic monitoring remains largely unexplored. To facilitate this exploration we present eTraM - a first-of-its-kind fully event-based traffic monitoring dataset. eTraM offers 10 hr of data from different traffic scenarios in various lighting and weather conditions providing a comprehensive overview of real-world situations. Providing 2M bounding box annotations it covers eight distinct classes of traffic participants ranging from vehicles to pedestrians and micro-mobility. eTraM's utility has been assessed using state-of-the-art methods for traffic participant detection including RVT RED and YOLOv8. We quantitatively evaluate the ability of event-based models to generalize on nighttime and unseen scenes. Our findings substantiate the compelling potential of leveraging event cameras for traffic monitoring opening new avenues for research and application. eTraM is available at https://eventbasedvision.github.io/eTraM.

Visual grounding refers to the process of associating natural language expressions with corresponding regions within an image. Existing benchmarks for visual grounding primarily operate within small-scale scenes with a few objects. Nevertheless recent advances in imaging technology have enabled the acquisition of gigapixel-level images providing high-resolution details in large-scale scenes containing numerous objects. To bridge this gap between imaging and computer vision benchmarks and make grounding more practically valuable we introduce a novel dataset named GigaGrounding designed to challenge visual grounding models in gigapixel-level large-scale scenes. We extensively analyze and compare the dataset with existing benchmarks demonstrating that GigaGrounding presents unique challenges such as large-scale scene understanding gigapixel-level resolution significant variations in object scales and the "multi-hop expressions". Furthermore we introduced a simple yet effective grounding approach which employs a "glance-to-zoom-in" paradigm and exhibits enhanced capabilities for addressing the GigaGrounding task. The dataset is available at www.gigavision.ai.

It is a well-known fact that the performance of deep learning models deteriorates when they encounter a distribution shift at test time. Test-time adaptation (TTA) algorithms have been proposed to adapt the model online while inferring test data. However existing research predominantly focuses on classification tasks through the optimization of batch normalization layers or classification heads but this approach limits its applicability to various model architectures like Transformers and makes it challenging to apply to other tasks such as object detection. In this paper we propose a novel online adaption approach for object detection in continually changing test domains considering which part of the model to update how to update it and when to perform the update. By introducing architecture-agnostic and lightweight adaptor modules and only updating these while leaving the pre-trained backbone unchanged we can rapidly adapt to new test domains in an efficient way and prevent catastrophic forgetting. Furthermore we present a practical and straightforward class-wise feature aligning method for object detection to resolve domain shifts. Additionally we enhance efficiency by determining when the model is sufficiently adapted or when additional adaptation is needed due to changes in the test distribution. Our approach surpasses baselines on widely used benchmarks achieving improvements of up to 4.9%p and 7.9%p in mAP for COCO ? COCO-corrupted and SHIFT respectively while maintaining about 20 FPS or higher. The implementation code is available at https://github.com/natureyoo/ContinualTTA_ObjectDetection.

Existing person re-identification methods have achieved remarkable advances in appearance-based identity association across homogeneous cameras such as ground-ground matching. However as a more practical scenario aerial-ground person re-identification (AGPReID) among heterogeneous cameras has received minimal attention. To alleviate the disruption of discriminative identity representation by dramatic view discrepancy as the most significant challenge in AGPReID the view-decoupled transformer (VDT) is proposed as a simple yet effective framework. Two major components are designed in VDT to decouple view-related and view-unrelated features namely hierarchical subtractive separation and orthogonal loss where the former separates these two features inside the VDT and the latter constrains these two to be independent. In addition we contribute a large-scale AGPReID dataset called CARGO consisting of five/eight aerial/ground cameras 5000 identities and 108563 images. Experiments on two datasets show that VDT is a feasible and effective solution for AGPReID surpassing the previous method on mAP/Rank1 by up to 5.0%/2.7% on CARGO and 3.7%/5.2% on AG-ReID keeping the same magnitude of computational complexity. Our project is available at https://github.com/LinlyAC/VDT-AGPReID

A versatile medical image segmentation model applicable to images acquired with diverse equipment and protocols can facilitate model deployment and maintenance. However building such a model typically demands a large diverse and fully annotated dataset which is challenging to obtain due to the labor-intensive nature of data curation. To address this challenge we propose a cost-effective alternative that harnesses multi-source data with only partial or sparse segmentation labels for training substantially reducing the cost of developing a versatile model. We devise strategies for model self-disambiguation prior knowledge incorporation and imbalance mitigation to tackle challenges associated with inconsistently labeled multi-source data including label ambiguity and modality dataset and class imbalances. Experimental results on a multi-modal dataset compiled from eight different sources for abdominal structure segmentation have demonstrated the effectiveness and superior performance of our method compared to state-of-the-art alternative approaches. We anticipate that its cost-saving features which optimize the utilization of existing annotated data and reduce annotation efforts for new data will have a significant impact in the field.

Achieving the optimal form of Visual Question Answering mandates a profound grasp of understanding grounding and reasoning within the intersecting domains of vision and language. Traditional VQA benchmarks have predominantly focused on simplistic tasks such as counting visual attributes and object detection which do not necessitate intricate cross-modal information understanding and inference. Motivated by the need for a more comprehensive evaluation we introduce a novel dataset comprising 23781 questions derived from 10124 image-text pairs. Specifically the task of this dataset requires the model to align multimedia representations of the same entity to implement multi-hop reasoning between image and text and finally use natural language to answer the question. Furthermore we evaluate this VTQA dataset comparing the performance of both state-of-the-art VQA models and our proposed baseline model the Key Entity Cross-Media Reasoning Network (KECMRN). The VTQA task poses formidable challenges for traditional VQA models underscoring its intrinsic complexity. Conversely KECMRN exhibits a modest improvement signifying its potential in multimedia entity alignment and multi-step reasoning. Our analysis underscores the diversity difficulty and scale of the VTQA task compared to previous multimodal QA datasets. In conclusion we anticipate that this dataset will serve as a pivotal resource for advancing and evaluating models proficient in multimedia entity alignment multi-step reasoning and open-ended answer generation. Our dataset and code is available at https://visual-text-qa.github.io/.

Data-driven three-dimensional parametric shape models of the human body have gained enormous popularity both for the analysis of visual data and for the generation of synthetic humans. Following a similar approach for animals does not scale to the multitude of existing animal species not to mention the difficulty of accessing subjects to scan in 3D. However we argue that for domestic species of great importance like the horse it is a highly valuable investment to put effort into gathering a large dataset of real 3D scans and learn a realistic 3D articulated shape model. We introduce VAREN a novel 3D articulated parametric shape model learned from 3D scans of many real horses. VAREN bridges synthesis and analysis tasks as the generated model instances have unprecedented realism while being able to represent horses of different sizes and shapes. Differently from previous body models VAREN has two resolutions an anatomical skeleton and interpretable learned pose-dependent deformations which are related to the body muscles. We show with experiments that this formulation has superior performance with respect to previous strategies for modeling pose-dependent deformations in the human body case while also being more compact and allowing an analysis of the relationship between articulation and muscle deformation during articulated motion.

When building classification systems with demographic fairness considerations there are two objectives to satisfy: 1) maximizing utility for the specific task and 2) ensuring fairness w.r.t. a known demographic attribute. These objectives often compete so optimizing both can lead to a trade-off between utility and fairness. While existing works acknowledge the trade-offs and study their limits two questions remain unanswered: 1) What are the optimal tradeoffs between utility and fairness? and 2) How can we numerically quantify these trade-offs from data for a desired prediction task and demographic attribute of interest? This paper addresses these questions. We introduce two utility-fairness trade-offs: the Data-Space and Label-Space Trade-off. The trade-offs reveal three regions within the utility-fairness plane delineating what is fully and partially possible and impossible. We propose U-FaTE a method to numerically quantify the trade-offs for a given prediction task and group fairness definition from data samples. Based on the trade-offs we introduce a new scheme for evaluating representations. An extensive evaluation of fair representation learning methods and representations from over 1000 pre-trained models revealed that most current approaches are far from the estimated and achievable fairness-utility trade-offs across multiple datasets and prediction tasks.

Given a set of images our goal is to map each image to a point in a feature space such that not only point proximity indicates visual similarity but where it is located directly encodes how prototypical the image is according to the dataset. Our key insight is to perform unsupervised feature learning in hyperbolic instead of Euclidean space where the distance between points still reflects image similarity yet we gain additional capacity for representing prototypicality with the location of the point: The closer it is to the origin the more prototypical it is. The latter property is simply emergent from optimizing the metric learning objective: The image similar to many training instances is best placed at the center of corresponding points in Euclidean space but closer to the origin in hyperbolic space. We propose an unsupervised feature learning algorithm in Hyperbolic space with sphere pACKing. HACK first generates uniformly packed particles in the Poincar'e ball of hyperbolic space and then assigns each image uniquely to a particle. With our feature mapper simply trained to spread out training instances in hyperbolic space we observe that images move closer to the origin with congealing - a warping process that aligns all the images and makes them appear more common and similar to each other validating our idea of unsupervised prototypicality discovery. We demonstrate that our data-driven prototypicality provides an easy and superior unsupervised instance selection to reduce sample complexity increase model generalization with atypical instances and robustness with typical ones.

Most models of visual attention aim at predicting either top-down or bottom-up control as studied using different visual search and free-viewing tasks. In this paper we propose the Human Attention Transformer (HAT) a single model that predicts both forms of attention control. HAT uses a novel transformer-based architecture and a simplified foveated retina that collectively create a spatio-temporal awareness akin to the dynamic visual working memory of humans. HAT not only establishes a new state-of-the-art in predicting the scanpath of fixations made during target-present and target-absent visual search and "taskless" free viewing but also makes human gaze behavior interpretable. Unlike previous methods that rely on a coarse grid of fixation cells and experience information loss due to fixation discretization HAT features a sequential dense prediction architecture and outputs a dense heatmap for each fixation thus avoiding discretizing fixations. HAT sets a new standard in computational attention which emphasizes effectiveness generality and interpretability. HAT's demonstrated scope and applicability will likely inspire the development of new attention models that can better predict human behavior in various attention-demanding scenarios. Code is available at https://github.com/cvlab-stonybrook/HAT.

This work delves into the task of pose-free novel view synthesis from stereo pairs a challenging and pioneering task in 3D vision. Our innovative framework unlike any before seamlessly integrates 2D correspondence matching camera pose estimation and NeRF rendering fostering a synergistic enhancement of these tasks. We achieve this through designing an architecture that utilizes a shared representation which serves as a foundation for enhanced 3D geometry understanding. Capitalizing on the inherent interplay between the tasks our unified framework is trained end-to-end with the proposed training strategy to improve overall model accuracy. Through extensive evaluations across diverse indoor and outdoor scenes from two real-world datasets we demonstrate that our approach achieves substantial improvement over previous methodologies especially in scenarios characterized by extreme viewpoint changes and the absence of accurate camera poses.

Despite the recent advances in unified image segmentation (IS) developing a unified video segmentation (VS) model remains a challenge. This is mainly because generic category-specified VS tasks need to detect all objects and track them across consecutive frames while prompt-guided VS tasks require re-identifying the target with visual/text prompts throughout the entire video making it hard to handle the different tasks with the same architecture. We make an attempt to address these issues and present a novel unified VS architecture namely UniVS by using prompts as queries. UniVS averages the prompt features of the target from previous frames as its initial query to explicitly decode masks and introduces a target-wise prompt cross-attention layer in the mask decoder to integrate prompt features in the memory pool. By taking the predicted masks of entities from previous frames as their visual prompts UniVS converts different VS tasks into prompt-guided target segmentation eliminating the heuristic inter-frame matching process. Our framework not only unifies the different VS tasks but also naturally achieves universal training and testing ensuring robust performance across different scenarios. UniVS shows a commendable balance between performance and universality on 10 challenging VS benchmarks covering video instance semantic panoptic object and referring segmentation tasks. Code can be found at https://github.com/MinghanLi/UniVS.

Parameter-efficient transfer learning (PETL) i.e. fine-tuning a small portion of parameters is an effective strategy for adapting pre-trained models to downstream domains. To further reduce the memory demand recent PETL works focus on the more valuable memory-efficient characteristic. In this paper we argue that the scalability adaptability and generalizability of state-of-the-art methods are hindered by structural dependency and pertinency on specific pre-trained backbones. To this end we propose a new memory-efficient PETL strategy Universal Parallel Tuning (UniPT) to mitigate these weaknesses. Specifically we facilitate the transfer process via a lightweight and learnable parallel network which consists of: 1) A parallel interaction module that decouples the sequential connections and processes the intermediate activations detachedly from the pre-trained network. 2) A confidence aggregation module that learns optimal strategies adaptively for integrating cross-layer features. We evaluate UniPT with different backbones (e.g. T5 VSEinfinity CLIP4Clip Clip-ViL and MDETR) on various vision-and-language and pure NLP tasks. Extensive ablations on 18 datasets have validated that UniPT can not only dramatically reduce memory consumption and outperform the best competitor but also achieve competitive performance over other plain PETL methods with lower training memory overhead. Our code is publicly available at: https://github.com/Paranioar/UniPT.

Accurate monocular metric depth estimation (MMDE) is crucial to solving downstream tasks in 3D perception and modeling. However the remarkable accuracy of recent MMDE methods is confined to their training domains. These methods fail to generalize to unseen domains even in the presence of moderate domain gaps which hinders their practical applicability. We propose a new model UniDepth capable of reconstructing metric 3D scenes from solely single images across domains. Departing from the existing MMDE methods UniDepth directly predicts metric 3D points from the input image at inference time without any additional information striving for a universal and flexible MMDE solution. In particular UniDepth implements a self-promptable camera module predicting dense camera representation to condition depth features. Our model exploits a pseudo-spherical output representation which disentangles camera and depth representations. In addition we propose a geometric invariance loss that promotes the invariance of camera-prompted depth features. Thorough evaluations on ten datasets in a zero-shot regime consistently demonstrate the superior performance of UniDepth even when compared with methods directly trained on the testing domains. Code and models are available at: github.com/lpiccinelli-eth/unidepth

The training of contemporary deep learning models heavily relies on publicly available data posing a risk of unauthorized access to online data and raising concerns about data privacy. Current approaches to creating unlearnable data involve incorporating small specially designed noises but these methods strictly limit data usability overlooking its potential usage in authorized scenarios. In this paper we extend the concept of unlearnable data to conditional data learnability and introduce UnGeneralizable Examples (UGEs). UGEs exhibit learnability for authorized users while maintaining unlearnability for potential hackers. The protector defines the authorized network and optimizes UGEs to match the gradients of the original data and its ungeneralizable version ensuring learnability. To prevent unauthorized learning UGEs are trained by maximizing a designated distance loss in a common feature space. Additionally to further safeguard the authorized side from potential attacks we introduce additional undistillation optimization. Experimental results on multiple datasets and various networks demonstrate that the proposed UGEs framework preserves data usability while reducing training performance on hacker networks even under different types of attacks.

Computer vision applications predict on digital images acquired by a camera from physical scenes through light. However conventional robustness benchmarks rely on perturbations in digitized images diverging from distribution shifts occurring in the image acquisition process. To bridge this gap we introduce a new distribution shift dataset ImageNet-ES comprising variations in environmental and camera sensor factors by directly capturing 202k images with a real camera in a controllable testbed. With the new dataset we evaluate out-of-distribution (OOD) detection and model robustness. We find that existing OOD detection methods do not cope with the covariate shifts in ImageNet-ES implying that the definition and detection of OOD should be revisited to embrace real-world distribution shifts. We also observe that the model becomes more robust in both ImageNet-C and -ES by learning environment and sensor variations in addition to existing digital augmentations. Lastly our results suggest that effective shift mitigation via camera sensor control can significantly improve performance without increasing model size. With these findings our benchmark may aid future research on robustness OOD and camera sensor control for computer vision. Our code and dataset are available at https://github.com/Edw2n/ImageNet-ES.

In ill-posed inverse problems it is commonly desirable to obtain insight into the full spectrum of plausible solutions rather than extracting only a single reconstruction. Information about the plausible solutions and their likelihoods is encoded in the posterior distribution. However for high-dimensional data this distribution is challenging to visualize. In this work we introduce a new approach for estimating and visualizing posteriors by employing energy-based models (EBMs) over low-dimensional subspaces. Specifically we train a conditional EBM that receives an input measurement and a set of directions that span some low-dimensional subspace of solutions and outputs the probability density function of the posterior within that space. We demonstrate the effectiveness of our method across a diverse range of datasets and image restoration problems showcasing its strength in uncertainty quantification and visualization. As we show our method outperforms a baseline that projects samples from a diffusion-based posterior sampler while being orders of magnitude faster. Furthermore it is more accurate than a baseline that assumes a Gaussian posterior.

Diffusion models have shown remarkable results for image generation editing and inpainting. Recent works explore diffusion models for 3D shape generation with neural implicit functions i.e. signed distance function and occupancy function. However they are limited to shapes with closed surfaces which prevents them from generating diverse 3D real-world contents containing open surfaces. In this work we present UDiFF a 3D diffusion model for unsigned distance fields (UDFs) which is capable to generate textured 3D shapes with open surfaces from text conditions or unconditionally. Our key idea is to generate UDFs in spatial-frequency domain with an optimal wavelet transformation which produces a compact representation space for UDF generation. Specifically instead of selecting an appropriate wavelet transformation which requires expensive manual efforts and still leads to large information loss we propose a data-driven approach to learn the optimal wavelet transformation for UDFs. We evaluate UDiFF to show our advantages by numerical and visual comparisons with the latest methods on widely used benchmarks. Page: https://weiqi-zhang.github.io/UDiFF.

Transductive inference has been widely investigated in few-shot image classification but completely overlooked in the recent fast growing literature on adapting vision-langage models like CLIP. This paper addresses the transductive zero-shot and few-shot CLIP classification challenge in which inference is performed jointly across a mini-batch of unlabeled query samples rather than treating each instance independently. This paper addresses the transductive zero-shot and few-shot CLIP classification challenge in which inference is performed jointly across a mini-batch of unlabeled query samples rather than treating each instance independently. We initially construct informative vision-text probability features leading to a classification problem on the unit simplex set. Inspired by Expectation-Maximization (EM) our optimization-based classifying objective models the data probability distribution for each class using a Dirichlet law. The minimization problem is then tackled with a novel block Majorization-Minimization algorithm which simultaneously estimates the distribution parameters and class assignments. Extensivenumerical experiments on 11 datasets underscore the benefits and efficacy of our batch inference approach. On zero-shot tasks with test batches of 75 samples our approach yields near 20% improvement in ImageNet accuracy over CLIP's zero-shot performance. Additionally we outperform state-of-the-art methods in the few-shot setting. Code is available at https://github.com/SegoleneMartin/transductive-CLIP.