Domain Adaptation

In this work we introduce Wonder3D a novel method for generating high-fidelity textured meshes from single-view images with remarkable efficiency. Recent methods based on the Score Distillation Sampling (SDS) loss methods have shown the potential to recover 3D geometry from 2D diffusion priors but they typically suffer from time-consuming per-shape optimization and inconsistent geometry. In contrast certain works directly produce 3D information via fast network inferences but their results are often of low quality and lack geometric details. To holistically improve the quality consistency and efficiency of image-to-3D tasks we propose a cross-domain diffusion model that generates multi-view normal maps and the corresponding color images. To ensure consistency we employ a multi-view cross-domain attention mechanism that facilitates information exchange across views and modalities. Lastly we introduce a geometry-aware normal fusion algorithm that extracts high-quality surfaces from the multi-view 2D representations in only 2 3 minutes. Our extensive evaluations demonstrate that our method achieves high-quality reconstruction results robust generalization and remarkable efficiency compared to prior works.

This paper presents a novel aerial-to-ground feature aggregation strategy tailored for the task of cross-view image-based geo-localization. Conventional vision-based methods heavily rely on matching ground-view image features with a pre-recorded image database often through establishing planar homography correspondences via a planar ground assumption. As such they tend to ignore features that are off-ground and not suited for handling visual occlusions leading to unreliable localization in challenging scenarios. We propose a Top-to-Ground Aggregation module that capitalizes aerial orthographic views to aggregate features down to the ground level leveraging reliable off-ground information to improve feature alignment. Furthermore we introduce a Cycle Domain Adaptation loss that ensures feature extraction robustness across domain changes. Additionally an Equidistant Re-projection loss is introduced to equalize the impact of all keypoints on orientation error leading to a more extended distribution of keypoints which benefits orientation estimation. On both KITTI and Ford Multi-AV datasets our method consistently achieves the lowest mean longitudinal and lateral translations across different settings and obtains the smallest orientation error when the initial pose is less accurate a more challenging setting. Further it can complete an entire route through continual vehicle pose estimation with initial vehicle pose given only at the starting point.

Open-Set Source-Free Domain Adaptation aims to transfer knowledge in realistic scenarios where the target domain has additional unknown classes compared to the limited-access source domain. Due to the absence of information on unknown classes existing methods mainly transfer knowledge of known classes while roughly grouping unknown classes as one attenuating the knowledge transfer and generalization. In contrast this paper advocates that exploring unknown classes can better identify known ones and proposes a domain adaptation model to transfer knowledge on known and unknown classes jointly. Specifically given a source pre-trained model we first introduce an unknown diffuser that can determine whether classes in space need to be split and merged through similarity measures to estimate and generate a wider class space distribution including known and unknown classes. Based on such a wider space distribution we enhance the reliability of known class knowledge in the source pre-trained model through contrastive constraint. Finally various supervision information including reliable known class knowledge and clustered pseudo-labels optimize the model for impressive knowledge transfer and generalization. Extensive experiments show that our network can achieve superior exploration and knowledge generalization on unknown classes while with excellent known class transfer. The code is available at https://github.com/xdwfl/UPUK.

In this work we tackle the problem of unsupervised domain adaptation (UDA) for video action recognition. Our approach which we call UNITE uses an image teacher model to adapt a video student model to the target domain. UNITE first employs self-supervised pre-training to promote discriminative feature learning on target domain videos using a teacher-guided masked distillation objective. We then perform self-training on masked target data using the video student model and image teacher model together to generate improved pseudolabels for unlabeled target videos. Our self-training process successfully leverages the strengths of both models to achieve strong transfer performance across domains. We evaluate our approach on multiple video domain adaptation benchmarks and observe significant improvements upon previously reported results.

Domain adaptation is a critical task in machine learning that aims to improve model performance on a target domain by leveraging knowledge from a related source domain. In this work we introduce Universal Semi-Supervised Domain Adaptation (UniSSDA) a practical yet challenging setting where the target domain is partially labeled and the source and target label space may not strictly match. UniSSDA is at the intersection of Universal Domain Adaptation (UniDA) and Semi-Supervised Domain Adaptation (SSDA): the UniDA setting does not allow for fine-grained categorization of target private classes not represented in the source domain while SSDA focuses on the restricted closed-set setting where source and target label spaces match exactly. Existing UniDA and SSDA methods are susceptible to common-class bias in UniSSDA settings where models overfit to data distributions of classes common to both domains at the expense of private classes. We propose a new prior-guided pseudo-label refinement strategy to reduce the reinforcement of common-class bias due to pseudo-labeling a common label propagation strategy in domain adaptation. We demonstrate the effectiveness of the proposed strategy on benchmark datasets Office-Home DomainNet and VisDA. The proposed strategy attains the best performance across UniSSDA adaptation settings and establishes a new baseline for UniSSDA.

This paper introduces Unified Language-driven Zero-shot Domain Adaptation (ULDA) a novel task setting that enables a single model to adapt to diverse target domains without explicit domain-ID knowledge. We identify the constraints in the existing language-driven zero-shot domain adaptation task particularly the requirement for domain IDs and domain-specific models which may restrict flexibility and scalability. To overcome these issues we propose a new framework for ULDA consisting of Hierarchical Context Alignment (HCA) Domain Consistent Representation Learning (DCRL) and Text-Driven Rectifier (TDR). These components work synergistically to align simulated features with target text across multiple visual levels retain semantic correlations between different regional representations and rectify biases between simulated and real target visual features respectively. Our extensive empirical evaluations demonstrate that this framework achieves competitive performance in both settings surpassing even the model that requires domain-ID showcasing its superiority and generalization ability. The proposed method is not only effective but also maintains practicality and efficiency as it does not introduce additional computational costs during inference. The code is available on the project website.

Test-time adaptation (TTA) aims at adapting a model pre-trained on the labeled source domain to the unlabeled target domain. Existing methods usually focus on improving TTA performance under covariate shifts while neglecting semantic shifts. In this paper we delve into a realistic open-set TTA setting where the target domain may contain samples from unknown classes. Many state-of-the-art closed-set TTA methods perform poorly when applied to open-set scenarios which can be attributed to the inaccurate estimation of data distribution and model confidence. To address these issues we propose a simple but effective framework called unified entropy optimization (UniEnt) which is capable of simultaneously adapting to covariate-shifted in-distribution (csID) data and detecting covariate-shifted out-of-distribution (csOOD) data. Specifically UniEnt first mines pseudo-csID and pseudo-csOOD samples from test data followed by entropy minimization on the pseudo-csID data and entropy maximization on the pseudo-csOOD data. Furthermore we introduce UniEnt+ to alleviate the noise caused by hard data partition leveraging sample-level confidence. Extensive experiments on CIFAR benchmarks and Tiny-ImageNet-C show the superiority of our framework. The code is available at https://github.com/gaozhengqing/UniEnt.

Source-free Domain Adaptation (SFDA) is an emerging and challenging research area that addresses the problem of unsupervised domain adaptation (UDA) without source data. Though numerous successful methods have been proposed for SFDA a theoretical understanding of why these methods work well is still absent. In this paper we shed light on the theoretical perspective of existing SFDA methods. Specifically we find that SFDA loss functions comprising discriminability and diversity losses work in the same way as the training objective in the theory of self-training based on the expansion assumption which shows the existence of the target error bound. This finding brings two novel insights that enable us to build an improved SFDA method comprising 1) Model Training with Auto-Adjusting Diversity Constraint and 2) Augmentation Training with Teacher-Student Framework yielding a better recognition performance. Extensive experiments on three benchmark datasets demonstrate the validity of the theoretical analysis and our method.

Single-source domain generalization (SDG) for object detection is a challenging yet essential task as the distribution bias of the unseen domain degrades the algorithm performance significantly. However existing methods attempt to extract domain-invariant features neglecting that the biased data leads the network to learn biased features that are non-causal and poorly generalizable. To this end we propose an Unbiased Faster R-CNN (UFR) for generalizable feature learning. Specifically we formulate SDG in object detection from a causal perspective and construct a Structural Causal Model (SCM) to analyze the data bias and feature bias in the task which are caused by scene confounders and object attribute confounders. Based on the SCM we design a Global-Local Transformation module for data augmentation which effectively simulates domain diversity and mitigates the data bias. Additionally we introduce a Causal Attention Learning module that incorporates a designed attention invariance loss to learn image-level features that are robust to scene confounders. Moreover we develop a Causal Prototype Learning module with an explicit instance constraint and an implicit prototype constraint which further alleviates the negative impact of object attribute confounders. Experimental results on five scenes demonstrate the prominent generalization ability of our method with an improvement of 3.9% mAP on the Night-Clear scene.

It is common to observe performance degradation when transferring models trained on some (source) datasets to target testing data due to a domain gap between them. Existing methods for bridging this gap such as domain adaptation (DA) may require the source data on which the model was trained (often not available) while others i.e. source-free DA require many passes through the testing data. We propose an online test-time adaptation method for depth completion the task of inferring a dense depth map from a single image and associated sparse depth map that closes the performance gap in a single pass. We first present a study on how the domain shift in each data modality affects model performance. Based on our observations that the sparse depth modality exhibits a much smaller covariate shift than the image we design an embedding module trained in the source domain that preserves a mapping from features encoding only sparse depth to those encoding image and sparse depth. During test time sparse depth features are projected using this map as a proxy for source domain features and are used as guidance to train a set of auxiliary parameters (i.e. adaptation layer) to align image and sparse depth features from the target test domain to that of the source domain. We evaluate our method on indoor and outdoor scenarios and show that it improves over baselines by an average of 21.1%. Code available at https://github.com/seobbro/TTA-depth-completion.

We study source-free unsupervised domain adaptation (SFUDA) for semantic segmentation which aims to adapt a source-trained model to the target domain without accessing the source data. Many works have been proposed to address this challenging problem among which uncertainty based self-training is a predominant approach. However without comprehensive denoising mechanisms they still largely fall into biased estimates when dealing with different domains and confirmation bias. In this paper we observe that pseudo-label noise is mainly contained in unstable samples in which the predictions of most pixels undergo significant variations during self-training. Inspired by this we propose a novel mechanism to denoise unstable samples with stable ones. Specifically we introduce the Stable Neighbor Denoising (SND) approach which effectively discovers highly correlated stable and unstable samples by nearest neighbor retrieval and guides the reliable optimization of unstable samples by bi-level learning. Moreover we compensate for the stable set by object-level object paste which can further eliminate the bias caused by less learned classes. Our SND enjoys two advantages. First SND does not require a specific segmentor structure endowing its universality. Second SND simultaneously addresses the issues of class domain and confirmation biases during adaptation ensuring its effectiveness. Extensive experiments show that SND consistently outperforms state-of-the-art methods in various SFUDA semantic segmentation settings. In addition SND can be easily integrated with other approaches obtaining further improvements. The source code will be publicly available.

Large vision-language models (VLMs) like CLIP have demonstrated good zero-shot learning performance in the unsupervised domain adaptation task. Yet most transfer approaches for VLMs focus on either the language or visual branches overlooking the nuanced interplay between both modalities. In this work we introduce a Unified Modality Separation (UniMoS) framework for unsupervised domain adaptation. Leveraging insights from modality gap studies we craft a nimble modality separation network that distinctly disentangles CLIP's features into language-associated and vision-associated components. Our proposed Modality-Ensemble Training (MET) method fosters the exchange of modality-agnostic information while maintaining modality-specific nuances. We align features across domains using a modality discriminator. Comprehensive evaluations on three benchmarks reveal our approach sets a new state-of-the-art with minimal computational costs. Code: https://github.com/TL-UESTC/UniMoS.

Source-Free Domain Adaptation (SFDA) aims to adapt a source model for a target domain with only access to unlabeled target training data and the source model pretrained on a supervised source domain. Relying on pseudo labeling and/or auxiliary supervision conventional methods are inevitably error-prone. To mitigate this limitation in this work we for the first time explore the potentials of off-the-shelf vision-language (ViL) multimodal models (e.g. CLIP) with rich whilst heterogeneous knowledge. We find that directly applying the ViL model to the target domain in a zero-shot fashion is unsatisfactory as it is not specialized for this particular task but largely generic. To make it task specific we propose a novel Distilling multImodal Foundation mOdel (DIFO) approach. Specifically DIFO alternates between two steps during adaptation: (i) Customizing the ViL model by maximizing the mutual information with the target model in a prompt learning manner (ii) Distilling the knowledge of this customized ViL model to the target model. For more fine-grained and reliable distillation we further introduce two effective regularization terms namely most-likely category encouragement and predictive consistency. Extensive experiments show that DIFO significantly outperforms the state-of-the-art alternatives. Code is here.

The pursuit of accurate 3D hand pose estimation stands as a keystone for understanding human activity in the realm of egocentric vision. The majority of existing estimation methods still rely on single-view images as input leading to potential limitations e.g. limited field-of-view and ambiguity in depth. To address these problems adding another camera to better capture the shape of hands is a practical direction. However existing multi-view hand pose estimation methods suffer from two main drawbacks: 1) Requiring multi-view annotations for training which are expensive. 2) During testing the model becomes inapplicable if camera parameters/layout are not the same as those used in training. In this paper we propose a novel Single-to-Dual-view adaptation (S2DHand) solution that adapts a pre-trained single-view estimator to dual views. Compared with existing multi-view training methods 1) our adaptation process is unsupervised eliminating the need for multi-view annotation. 2) Moreover our method can handle arbitrary dual-view pairs with unknown camera parameters making the model applicable to diverse camera settings. Specifically S2DHand is built on certain stereo constraints including pair-wise cross-view consensus and invariance of transformation between both views. These two stereo constraints are used in a complementary manner to generate pseudo-labels allowing reliable adaptation. Evaluation results reveal that S2DHand achieves significant improvements on arbitrary camera pairs under both in-dataset and cross-dataset settings and outperforms existing adaptation methods with leading performance. Project page: https://github.com/ut-vision/S2DHand.

Due to its promising results density map regression has been widely employed for image-based crowd counting. The approach however often suffers from severe performance degradation when tested on data from unseen scenarios the so-called "domain shift" problem. To address the problem we investigate in this work single domain generalization (SDG) for crowd counting. The existing SDG approaches are mainly for image classification and segmentation and can hardly be extended to our case due to its regression nature and label ambiguity (i.e. ambiguous pixel-level ground truths). We propose MPCount a novel effective SDG approach even for narrow source distribution. MPCount stores diverse density values for density map regression and reconstructs domain-invariant features by means of only one memory bank a content error mask and attention consistency loss. By partitioning the image into grids it employs patch-wise classification as an auxiliary task to mitigate label ambiguity. Through extensive experiments on different datasets MPCount is shown to significantly improve counting accuracy compared to the state of the art under diverse scenarios unobserved in the training data characterized by narrow source distribution. Code is available at https://github.com/Shimmer93/MPCount.

In this paper we delve into the nuanced challenge of tailoring the Segment Anything Models (SAMs) for integration with event data with the overarching objective of attaining robust and universal object segmentation within the event-centric domain. One pivotal issue at the heart of this endeavor is the precise alignment and calibration of embeddings derived from event-centric data such that they harmoniously coincide with those originating from RGB imagery. Capitalizing on the vast repositories of datasets with paired events and RGB images our proposition is to harness and extrapolate the profound knowledge encapsulated within the pre-trained SAM framework. As a cornerstone to achieving this we introduce a multi-scale feature distillation methodology. This methodology rigorously optimizes the alignment of token embeddings originating from event data with their RGB image counterparts thereby preserving and enhancing the robustness of the overall architecture. Considering the distinct significance that token embeddings from intermediate layers hold for higher-level embeddings our strategy is centered on accurately calibrating the pivotal token embeddings. This targeted calibration is aimed at effectively managing the discrepancies in high-level embeddings originating from both the event and image domains. Extensive experiments on different datasets demonstrate the effectiveness of the proposed distillation method. Code in https://github.com/happychenpipi/EventSAM.

Active Domain Adaptation (ADA) aims to maximally boost model adaptation in a new target domain by actively selecting a limited number of target data to annotate. This setting neglects the more practical scenario where training data are collected from multiple sources. This motivates us to extend ADA from a single source domain to multiple source domains termed Multi-source Active Domain Adaptation (MADA). Not surprisingly we find that most traditional ADA methods cannot work directly in such a setting mainly due to the excessive domain gap introduced by all the source domains. Considering this we propose a Detective framework that comprehensively considers the domain shift between multi-source domains and target domains to detect the informative target samples. Specifically the Detective leverages a dynamic Domain Adaptation (DA) model that learns how to adapt the model's parameters to fit the union of multi-source domains. This enables an approximate single-source domain modeling by the dynamic model. We then comprehensively measure both domain uncertainty and predictive uncertainty in the target domain to detect informative target samples using evidential deep learning thereby mitigating uncertainty miscalibration. Experiments demonstrate that our solution outperforms existing methods by a considerable margin on three domain adaptation benchmarks.

Domain generalization aims to solve the challenge of Out-of-Distribution (OOD) generalization by leveraging common knowledge learned from multiple training domains to generalize to unseen test domains. To accurately evaluate the OOD generalization ability it is required that test data information is unavailable. However the current domain generalization protocol may still have potential test data information leakage. This paper examines the risks of test data information leakage from two aspects of the current evaluation protocol: supervised pretraining on ImageNet and oracle model selection. We propose modifications to the current protocol that we should employ self-supervised pretraining or train from scratch instead of employing the current supervised pretraining and we should use multiple test domains. These would result in a more precise evaluation of OOD generalization ability. We also rerun the algorithms with the modified protocol and introduce new leaderboards to encourage future research in domain generalization with a fairer comparison.

Developing generalizable manipulation skills is a core challenge in embodied AI. This includes generalization across diverse task configurations encompassing variations in object shape density friction coefficient and external disturbances such as forces applied to the robot. Rapid Motor Adaptation (RMA) offers a promising solution to this challenge. It posits that essential hidden variables influencing an agent's task performance such as object mass and shape can be effectively inferred from the agent's action and proprioceptive history. Drawing inspiration from RMA in locomotion and in-hand rotation we use depth perception to develop agents tailored for rapid motor adaptation in a variety of manipulation tasks. We evaluated our agents on four challenging tasks from the Maniskill2 benchmark namely pick-and-place operations with hundreds of objects from the YCB and EGAD datasets peg insertion with precise position and orientation and operating a variety of faucets and handles with customized environment variations. Empirical results demonstrate that our agents surpass state-of-the-art methods like automatic domain randomization and vision-based policies obtaining better generalization performance and sample efficiency.

Recent self-training techniques have shown notable improvements in unsupervised domain adaptation for 3D object detection (3D UDA). These techniques typically select pseudo labels i.e. 3D boxes to supervise models for the target domain. However this selection process inevitably introduces unreliable 3D boxes in which 3D points cannot be definitively assigned as foreground or background. Previous techniques mitigate this by reweighting these boxes as pseudo labels but these boxes can still poison the training process. To resolve this problem in this paper we propose a novel pseudo label refinery framework. Specifically in the selection process to improve the reliability of pseudo boxes we propose a complementary augmentation strategy. This strategy involves either removing all points within an unreliable box or replacing it with a high-confidence box. Moreover the point numbers of instances in high-beam datasets are considerably higher than those in low-beam datasets also degrading the quality of pseudo labels during the training process. We alleviate this issue by generating additional proposals and aligning RoI features across different domains. Experimental results demonstrate that our method effectively enhances the quality of pseudo labels and consistently surpasses the state-of-the-art methods on six autonomous driving benchmarks. Code will be available at https://github.com/Zhanwei-Z/PERE.