In this work we focus on learning facial representations that can be adapted to train effective face recognition models particularly in the absence of labels. Firstly compared with existing labelled face datasets a vastly larger magnitude of unlabeled faces exists in the real world. We explore the learning strategy of these unlabeled facial images through self-supervised pretraining to transfer generalized face recognition performance. Moreover motivated by one recent finding that is the face saliency area is critical for face recognition in contrast to utilizing random cropped blocks of images for constructing augmentations in pretraining we utilize patches localized by extracted facial landmarks. This enables our method - namely Landmark-based Facial Self-supervised learning (LAFS) to learn key representation that is more critical for face recognition. We also incorporate two landmark-specific augmentations which introduce more diversity of landmark information to further regularize the learning. With learned landmark-based facial representations we further adapt the representation for face recognition with regularization mitigating variations in landmark positions. Our method achieves significant improvement over the state-of-the-art on multiple face recognition benchmarks especially on more challenging few-shot scenarios. The code is available at https://github.com/szlbiubiubiu/LAFS_CVPR2024
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Insect-Foundation: A Foundation Model and Large-scale 1M Dataset for Visual Insect Understanding
PDF ↗In precision agriculture the detection and recognition of insects play an essential role in the ability of crops to grow healthy and produce a high-quality yield. The current machine vision model requires a large volume of data to achieve high performance. However there are approximately 5.5 million different insect species in the world. None of the existing insect datasets can cover even a fraction of them due to varying geographic locations and acquisition costs. In this paper we introduce a novel "Insect-1M" dataset a game-changing resource poised to revolutionize insect-related foundation model training. Covering a vast spectrum of insect species our dataset including 1 million images with dense identification labels of taxonomy hierarchy and insect descriptions offers a panoramic view of entomology enabling foundation models to comprehend visual and semantic information about insects like never before. Then to efficiently establish an Insect Foundation Model we develop a micro-feature self-supervised learning method with a Patch-wise Relevant Attention mechanism capable of discerning the subtle differences among insect images. In addition we introduce Description Consistency loss to improve micro-feature modeling via insect descriptions. Through our experiments we illustrate the effectiveness of our proposed approach in insect modeling and achieve State-of-the-Art performance on standard benchmarks of insect-related tasks. Our Insect Foundation Model and Dataset promise to empower the next generation of insect-related vision models bringing them closer to the ultimate goal of precision agriculture.
Learning 3D models of all animals in nature requires massively scaling up existing solutions. With this ultimate goal in mind we develop 3D-Fauna an approach that learns a pan-category deformable 3D animal model for more than 100 animal species jointly. One crucial bottleneck of modeling animals is the limited availability of training data which we overcome by learning our model from 2D Internet images. We show that prior approaches which are category-specific fail to generalize to rare species with limited training images. We address this challenge by introducing the Semantic Bank of Skinned Models (SBSM) which automatically discovers a small set of base animal shapes by combining geometric inductive priors with semantic knowledge implicitly captured by an off-the-shelf self-supervised feature extractor. To train such a model we also contribute a new large-scale dataset of diverse animal species. At inference time given a single image of any quadruped animal our model reconstructs an articulated 3D mesh in a feed-forward manner in seconds.
We present the Locally Adaptive Morphable Model (LAMM) a highly flexible Auto-Encoder (AE) framework for learning to generate and manipulate 3D meshes. We train our architecture following a simple self-supervised training scheme in which input displacements over a set of sparse control vertices are used to overwrite the encoded geometry in order to transform one training sample into another. During inference our model produces a dense output that adheres locally to the specified sparse geometry while maintaining the overall appearance of the encoded object. This approach results in state-of-the-art performance in both disentangling manipulated geometry and 3D mesh reconstruction. To the best of our knowledge LAMM is the first end-to-end framework that enables direct local control of 3D vertex geometry in a single forward pass. A very efficient computational graph allows our network to train with only a fraction of the memory required by previous methods and run faster during inference generating 12k vertex meshes at >60fps on a single CPU thread. We further leverage local geometry control as a primitive for higher level editing operations and present a set of derivative capabilities such as swapping and sampling object parts. Code and pretrained models can be found at https://github.com/michaeltrs/LAMM.
We present a new self-supervised approach SelfPose3d for estimating 3d poses of multiple persons from multiple camera views. Unlike current state-of-the-art fully-supervised methods our approach does not require any 2d or 3d ground-truth poses and uses only the multi-view input images from a calibrated camera setup and 2d pseudo poses generated from an off-the-shelf 2d human pose estimator. We propose two self-supervised learning objectives: self-supervised person localization in 3d space and self-supervised 3d pose estimation. We achieve self-supervised 3d person localization by training the model on synthetically generated 3d points serving as 3d person root positions and on the projected root-heatmaps in all the views. We then model the 3d poses of all the localized persons with a bottleneck representation map them onto all views obtaining 2d joints and render them using 2d Gaussian heatmaps in an end-to-end differentiable manner. Afterwards we use the corresponding 2d joints and heatmaps from the pseudo 2d poses for learning. To alleviate the intrinsic inaccuracy of the pseudo labels we propose an adaptive supervision attention mechanism to guide the self-supervision. Our experiments and analysis on three public benchmark datasets including Panoptic Shelf and Campus show the effectiveness of our approach which is comparable to fully-supervised methods. Code is available at https://github.com/CAMMA-public/SelfPose3D.
Recently the advancement of self-supervised learning techniques like masked autoencoders (MAE) has greatly influenced visual representation learning for images and videos. Nevertheless it is worth noting that the predominant approaches in existing masked image / video modeling rely excessively on resource-intensive vision transformers (ViTs) as the feature encoder. In this paper we propose a new approach termed as VideoMAC which combines video masked autoencoders with resource-friendly ConvNets. Specifically VideoMAC employs symmetric masking on randomly sampled pairs of video frames. To prevent the issue of mask pattern dissipation we utilize ConvNets which are implemented with sparse convolutional operators as encoders. Simultaneously we present a simple yet effective masked video modeling (MVM) approach a dual encoder architecture comprising an online encoder and an exponential moving average target encoder aimed to facilitate inter-frame reconstruction consistency in videos. Additionally we demonstrate that VideoMAC empowering classical (ResNet) / modern (ConvNeXt) convolutional encoders to harness the benefits of MVM outperforms ViT-based approaches on downstream tasks including video object segmentation (+5.2% / 6.4% \mathcal J &\mathcal F ) body part propagation (+6.3% / 3.1% mIoU) and human pose tracking (+10.2% / 11.1% PCK@0.1).
Unsupervised landmarks discovery (ULD) for an object category is a challenging computer vision problem. In pursuit of developing a robust ULD framework we explore the potential of a recent paradigm of self-supervised learning algorithms known as diffusion models. Some recent works have shown that these models implicitly contain important correspondence cues. Towards harnessing the potential of diffusion models for ULD task we make the following core contributions. First we propose a ZeroShot ULD baseline based on simple clustering of random pixel locations with nearest neighbour matching. It delivers better results than the existing ULD methods. Second motivated by the ZeroShot performance we develop a ULD algorithm based on diffusion features using self-training and clustering which also outperforms prior methods by notable margins. Third we introduce a new proxy task based on generating latent pose codes and also propose a two-stage clustering mechanism to facilitate effective pseudo-labeling resulting in a significant performance improvement. Overall our approach consistently outperforms state-of-the-art methods on four challenging benchmarks AFLW MAFL CatHeads and LS3D by significant margins.
The perception of autonomous vehicles using radars has attracted increased research interest due its ability to operate in fog and bad weather. However training radar models is hindered by the cost and difficulty of annotating large-scale radar data. To overcome this bottleneck we propose a self-supervised learning framework to leverage the large amount of unlabeled radar data to pre-train radar-only embeddings for self-driving perception tasks. The proposed method combines radar-to-radar and radar-to-vision contrastive losses to learn a general representation from unlabeled radar heatmaps paired with their corresponding camera images. When used for downstream object detection we demonstrate that the proposed self-supervision framework can improve the accuracy of state-of-the-art supervised baselines by 5.8% in mAP. Code is available at https://github.com/yiduohao/Radical.
We present a 3D-aware one-shot head reenactment method based on a fully volumetric neural disentanglement framework for source appearance and driver expressions. Our method is real-time and produces high-fidelity and view-consistent output suitable for 3D teleconferencing systems based on holographic displays. Existing cutting-edge 3D-aware reenactment methods often use neural radiance fields or 3D meshes to produce view-consistent appearance encoding but at the same time they rely on linear face models such as 3DMM to achieve its disentanglement with facial expressions. As a result their reenactment results often exhibit identity leakage from the driver or have unnatural expressions. To address these problems we propose a neural self-supervised disentanglement approach that lifts both the source image and driver video frame into a shared 3D volumetric representation based on tri-planes. This representation can then be freely manipulated with expression tri-planes extracted from the driving images and rendered from an arbitrary view using neural radiance fields. We achieve this disentanglement via self-supervised learning on a large in-the-wild video dataset. We further introduce a highly effective fine-tuning approach to improve the generalizability of the 3D lifting using the same real-world data. We demonstrate state-of-the-art performance on a wide range of datasets and also showcase high-quality 3D-aware head reenactment on highly challenging and diverse subjects including non-frontal head poses and complex expressions for both source and driver.
Hunting Attributes: Context Prototype-Aware Learning for Weakly Supervised Semantic Segmentation
PDF ↗Recent weakly supervised semantic segmentation (WSSS) methods strive to incorporate contextual knowledge to improve the completeness of class activation maps (CAM). In this work we argue that the knowledge bias between instances and contexts affects the capability of the prototype to sufficiently understand instance semantics. Inspired by prototype learning theory we propose leveraging prototype awareness to capture diverse and fine-grained feature attributes of instances. The hypothesis is that contextual prototypes might erroneously activate similar and frequently co-occurring object categories due to this knowledge bias. Therefore we propose to enhance the prototype representation ability by mitigating the bias to better capture spatial coverage in semantic object regions. With this goal we present a Context Prototype-Aware Learning (CPAL) strategy which leverages semantic context to enrich instance comprehension. The core of this method is to accurately capture intra-class variations in object features through context-aware prototypes facilitating the adaptation to the semantic attributes of various instances. We design feature distribution alignment to optimize prototype awareness aligning instance feature distributions with dense features. In addition a unified training framework is proposed to combine label-guided classification supervision and prototypes-guided self-supervision. Experimental results on PASCAL VOC 2012 and MS COCO 2014 show that CPAL significantly improves off-the-shelf methods and achieves state-of-the-art performance. The project is available at \href https://github.com/Barrett-python/CPAL https://github.com/Barrett-python/CPAL.
UniGarmentManip: A Unified Framework for Category-Level Garment Manipulation via Dense Visual Correspondence
PDF ↗Garment manipulation (e.g. unfolding folding and hanging clothes) is essential for future robots to accomplish home-assistant tasks while highly challenging due to the diversity of garment configurations geometries and deformations. Although able to manipulate similar shaped garments in a certain task previous works mostly have to design different policies for different tasks could not generalize to garments with diverse geometries and often rely heavily on human-annotated data. In this paper we leverage the property that garments in a certain category have similar structures and then learn the topological dense (point-level) visual correspondence among garments in the category level with different deformations in the self-supervised manner. The topological correspondence can be easily adapted to the functional correspondence to guide the manipulation policies for various downstream tasks within only one or few-shot demonstrations. Experiments over garments in 3 different categories on 3 representative tasks in diverse scenarios using one or two arms taking one or more steps inputting flat or messy garments demonstrate the effectiveness of our proposed method. Project page: https://warshallrho.github.io/unigarmentmanip.
Image signal processing (ISP) pipeline plays a fundamental role in digital cameras which converts raw Bayer sensor data to RGB images. However ISP-generated images usually suffer from imperfections due to the compounded degradations that stem from sensor noises demosaicing noises compression artifacts and possibly adverse effects of erroneous ISP hyperparameter settings such as ISO and gamma values. In a general sense these ISP imperfections can be considered as degradations. The highly complex mechanisms of ISP degradations some of which are even unknown pose great challenges to the generalization capability of deep neural networks (DNN) for image restoration and to their adaptability to downstream tasks. To tackle the issues we propose a novel DNN approach to learn degradation-independent representations (DiR) through the refinement of a self-supervised learned baseline representation. The proposed DiR learning technique has remarkable domain generalization capability and consequently it outperforms state-of-the-art methods across various downstream tasks including blind image restoration object detection and instance segmentation as verified in our experiments.
Visual-inertial odometry (VIO) has demonstrated remarkable success due to its low-cost and complementary sensors. However existing VIO methods lack the generalization ability to adjust to different environments and sensor attributes. In this paper we propose Adaptive VIO a new monocular visual-inertial odometry that combines online continual learning with traditional nonlinear optimization. Adaptive VIO comprises two networks to predict visual correspondence and IMU bias. Unlike end-to-end approaches that use networks to fuse the features from two modalities (camera and IMU) and predict poses directly we combine neural networks with visual-inertial bundle adjustment in our VIO system. The optimized estimates will be fed back to the visual and IMU bias networks refining the networks in a self-supervised manner. Such a learning-optimization-combined framework and feedback mechanism enable the system to perform online continual learning. Experiments demonstrate that our Adaptive VIO manifests adaptive capability on EuRoC and TUM-VI datasets. The overall performance exceeds the currently known learning-based VIO methods and is comparable to the state-of-the-art optimization-based methods.
Visual sound source localization poses a significant challenge in identifying the semantic region of each sounding source within a video. Existing self-supervised and weakly supervised source localization methods struggle to accurately distinguish the semantic regions of each sounding object particularly in multi-source mixtures. These methods often rely on audio-visual correspondence as guidance which can lead to substantial performance drops in complex multi-source localization scenarios. The lack of access to individual source sounds in multi-source mixtures during training exacerbates the difficulty of learning effective audio-visual correspondence for localization. To address this limitation in this paper we propose incorporating the text modality as an intermediate feature guide using tri-modal joint embedding models (e.g. AudioCLIP) to disentangle the semantic audio-visual source correspondence in multi-source mixtures. Our framework dubbed T-VSL begins by predicting the class of sounding entities in mixtures. Subsequently the textual representation of each sounding source is employed as guidance to disentangle fine-grained audio-visual source correspondence from multi-source mixtures leveraging the tri-modal AudioCLIP embedding. This approach enables our framework to handle a flexible number of sources and exhibits promising zero-shot transferability to unseen classes during test time. Extensive experiments conducted on the MUSIC VGGSound and VGGSound-Instruments datasets demonstrate significant performance improvements over state-of-the-art methods. Code is released at https://github.com/enyac-group/T-VSL/tree/main.
Image denoising is a fundamental task in computer vision. While prevailing deep learning-based supervised and self-supervised methods have excelled in eliminating in-distribution noise their susceptibility to out-of-distribution (OOD) noise remains a significant challenge. The recent emergence of contrastive language-image pre-training (CLIP) model has showcased exceptional capabilities in open-world image recognition and segmentation. Yet the potential for leveraging CLIP to enhance the robustness of low-level tasks remains largely unexplored. This paper uncovers that certain dense features extracted from the frozen ResNet image encoder of CLIP exhibit distortion-invariant and content-related properties which are highly desirable for generalizable denoising. Leveraging these properties we devise an asymmetrical encoder-decoder denoising network which incorporates dense features including the noisy image and its multi-scale features from the frozen ResNet encoder of CLIP into a learnable image decoder to achieve generalizable denoising. The progressive feature augmentation strategy is further proposed to mitigate feature overfitting and improve the robustness of the learnable decoder. Extensive experiments and comparisons conducted across diverse OOD noises including synthetic noise real-world sRGB noise and low-dose CT image noise demonstrate the superior generalization ability of our method.
SD2Event:Self-supervised Learning of Dynamic Detectors and Contextual Descriptors for Event Cameras
PDF ↗Event cameras offer many advantages over traditional frame-based cameras such as high dynamic range and low latency. Therefore event cameras are widely applied in diverse computer vision applications where event-based keypoint detection is a fundamental task. However achieving robust event-based keypoint detection remains challenging because the ground truth of event keypoints is difficult to obtain descriptors extracted by CNN usually lack discriminative ability in the presence of intense noise and fixed keypoint detectors are limited in detecting varied keypoint patterns. To address these challenges a novel event-based keypoint detection method is proposed by learning dynamic detectors and contextual descriptors in a self-supervised manner (SD2Event) including a contextual feature descriptor learning (CFDL) module and a dynamic keypoint detector learning (DKDL) module. The proposed SD2Event enjoys several merits. First the proposed CFDL module can model long-range contexts efficiently and effectively. Second the DKDL module generates dynamic keypoint detectors which can detect keypoints with diverse patterns across various event streams. Third the proposed self-supervised signals can guide the model's adaptation to event data. Extensive experimental results on three challenging benchmarks show that our proposed method significantly outperforms stateof-the-art event-based keypoint detection methods.
Systematic Comparison of Semi-supervised and Self-supervised Learning for Medical Image Classification
PDF ↗In typical medical image classification problems labeled data is scarce while unlabeled data is more available. Semi-supervised learning and self-supervised learning are two different research directions that can improve accuracy by learning from extra unlabeled data. Recent methods from both directions have reported significant gains on traditional benchmarks. Yet past benchmarks do not focus on medical tasks and rarely compare self- and semi- methods together on an equal footing. Furthermore past benchmarks often handle hyperparameter tuning suboptimally. First they may not tune hyperparameters at all leading to underfitting. Second when tuning does occur it often unrealistically uses a labeled validation set that is much larger than the training set. Therefore currently published rankings might not always corroborate with their practical utility This study contributes a systematic evaluation of self- and semi- methods with a unified experimental protocol intended to guide a practitioner with scarce overall labeled data and a limited compute budget. We answer two key questions: Can hyperparameter tuning be effective with realistic-sized validation sets? If so when all methods are tuned well which self- or semi-supervised methods achieve the best accuracy? Our study compares 13 representative semi- and self-supervised methods to strong labeled-set-only baselines on 4 medical datasets. From 20000+ GPU hours of computation we provide valuable best practices to resource-constrained practitioners: hyperparameter tuning is effective and the semi-supervised method known as MixMatch delivers the most reliable gains across 4 datasets.
Self-supervised learning (SSL) has been successful in building patch embeddings of small histology images (e.g. 224 x 224 pixels) but scaling these models to learn slide embeddings from the entirety of giga-pixel whole-slide images (WSIs) remains challenging. Here we leverage complementary information from gene expression profiles to guide slide representation learning using multi-modal pre-training. Expression profiles constitute highly detailed molecular descriptions of a tissue that we hypothesize offer a strong task-agnostic training signal for learning slide embeddings. Our slide and expression (S+E) pretraining strategy called TANGLE employs modality-specific encoders the outputs of which are aligned via contrastive learning. TANGLE was pre-trained on samples from three different organs: liver (n=6597 S+E pairs) breast (n=1020) and lung (n=1012) from two different species (Homo sapiens and Rattus norvegicus). Across three independent test datasets consisting of 1265 breast WSIs 1946 lung WSIs and 4584 liver WSIs TANGLE shows significantly better few-shot performance compared to supervised and SSL baselines. When assessed using prototype-based classification and slide retrieval TANGLE also shows a substantial performance improvement over all baselines. Code available at https://github.com/mahmoodlab/TANGLE.
With the rapid growth in deepfake video content we require improved and generalizable methods to detect them. Most existing detection methods either use uni-modal cues or rely on supervised training to capture the dissonance between the audio and visual modalities. While the former disregards the audio-visual correspondences entirely the latter predominantly focuses on discerning audio-visual cues within the training corpus thereby potentially overlooking correspondences that can help detect unseen deepfakes. We present Audio-Visual Feature Fusion (AVFF) a two-stage cross-modal learning method that explicitly captures the correspondence between the audio and visual modalities for improved deepfake detection. The first stage pursues representation learning via self-supervision on real videos to capture the intrinsic audio-visual correspondences. To extract rich cross-modal representations we use contrastive learning and autoencoding objectives and introduce a novel audio-visual complementary masking and feature fusion strategy. The learned representations are tuned in the second stage where deepfake classification is pursued via supervised learning on both real and fake videos. Extensive experiments and analysis suggest that our novel representation learning paradigm is highly discriminative in nature. We report 98.6% accuracy and 99.1% AUC on the FakeAVCeleb dataset outperforming the current audio-visual state-of-the-art by 14.9% and 9.9% respectively.
Mitigating Object Dependencies: Improving Point Cloud Self-Supervised Learning through Object Exchange
PDF ↗In the realm of point cloud scene understanding particularly in indoor scenes objects are arranged following human habits resulting in objects of certain semantics being closely positioned and displaying notable inter-object correlations. This can create a tendency for neural networks to exploit these strong dependencies bypassing the individual object patterns. To address this challenge we introduce a novel self-supervised learning (SSL) strategy. Our approach leverages both object patterns and contextual cues to produce robust features. It begins with the formulation of an object-exchanging strategy where pairs of objects with comparable sizes are exchanged across different scenes effectively disentangling the strong contextual dependencies. Subsequently we introduce a context-aware feature learning strategy which encodes object patterns without relying on their specific context by aggregating object features across various scenes. Our extensive experiments demonstrate the superiority of our method over existing SSL techniques further showing its better robustness to environmental changes. Moreover we showcase the applicability of our approach by transferring pre-trained models to diverse point cloud datasets.