CVPR 2024 论文列表

Weakly supervised semantic segmentation (WSSS) with image-level labels aims to achieve segmentation tasks without dense annotations. However attributed to the frequent coupling of co-occurring objects and the limited supervision from image-level labels the challenging co-occurrence problem is widely present and leads to false activation of objects in WSSS. In this work we devise a 'Separate and Conquer' scheme SeCo to tackle this issue from dimensions of image space and feature space. In the image space we propose to 'separate' the co-occurring objects with image decomposition by subdividing images into patches. Importantly we assign each patch a category tag from Class Activation Maps (CAMs) which spatially helps remove the co-context bias and guide the subsequent representation. In the feature space we propose to 'conquer' the false activation by enhancing semantic representation with multi-granularity knowledge contrast. To this end a dual-teacher-single-student architecture is designed and tag-guided contrast is conducted which guarantee the correctness of knowledge and further facilitate the discrepancy among co-contexts. We streamline the multi-staged WSSS pipeline end-to-end and tackle this issue without external supervision. Extensive experiments are conducted validating the efficiency of our method and the superiority over previous single-staged and even multi-staged competitors on PASCAL VOC and MS COCO. Code is available at https://github.com/zwyang6/SeCo.git.

Capturing and preserving motion semantics is essential to motion retargeting between animation characters. However most of the previous works neglect the semantic information or rely on human-designed joint-level representations. Here we present a novel Semantics-aware Motion reTargeting (SMT) method with the advantage of vision-language models to extract and maintain meaningful motion semantics. We utilize a differentiable module to render 3D motions. Then the high-level motion semantics are incorporated into the motion retargeting process by feeding the vision-language model with the rendered images and aligning the extracted semantic embeddings. To ensure the preservation of fine-grained motion details and high-level semantics we adopt a two-stage pipeline consisting of skeleton-aware pre-training and fine-tuning with semantics and geometry constraints. Experimental results show the effectiveness of the proposed method in producing high-quality motion retargeting results while accurately preserving motion semantics. Project page can be found at https://sites.google.com/view/smtnet.

This paper addresses an interesting yet challenging problem-- source-free unsupervised domain adaptation (SFUDA) for pinhole-to-panoramic semantic segmentation--given only a pinhole image-trained model (i.e. source) and unlabeled panoramic images (i.e. target). Tackling this problem is nontrivial due to the semantic mismatches style discrepancies and inevitable distortion of panoramic images. To this end we propose a novel method that utilizes Tangent Projection (TP) as it has less distortion and meanwhile slits the equirectangular projection (ERP) with a fixed FoV to mimic the pinhole images. Both projections are shown effective in extracting knowledge from the source model. However the distinct projection discrepancies between source and target domains impede the direct knowledge transfer; thus we propose a panoramic prototype adaptation module (PPAM) to integrate panoramic prototypes from the extracted knowledge for adaptation. We then impose the loss constraints on both predictions and prototypes and propose a cross-dual attention module (CDAM) at the feature level to better align the spatial and channel characteristics across the domains and projections. Both knowledge extraction and transfer processes are synchronously updated to reach the best performance. Extensive experiments on the synthetic and real-world benchmarks including outdoor and indoor scenarios demonstrate that our method achieves significantly better performance than prior SFUDA methods for pinhole-to-panoramic adaptation.

Single-point annotation in visual tasks with the goal of minimizing labeling costs is becoming increasingly prominent in research. Recently visual foundation models such as Segment Anything (SAM) have gained widespread usage due to their robust zero-shot capabilities and exceptional annotation performance. However SAM's class-agnostic output and high confidence in local segmentation introduce semantic ambiguity posing a challenge for precise category-specific segmentation. In this paper we introduce a cost-effective category-specific segmenter using SAM. To tackle this challenge we have devised a Semantic-Aware Instance Segmentation Network (SAPNet) that integrates Multiple Instance Learning (MIL) with matching capability and SAM with point prompts. SAPNet strategically selects the most representative mask proposals generated by SAM to supervise segmentation with a specific focus on object category information. Moreover we introduce the Point Distance Guidance and Box Mining Strategy to mitigate inherent challenges: group and local issues in weakly supervised segmentation. These strategies serve to further enhance the overall segmentation performance. The experimental results on Pascal VOC and COCO demonstrate the promising performance of our proposed SAPNet emphasizing its semantic matching capabilities and its potential to advance point-prompted instance segmentation. The code is available at https://github.com/zhaoyangwei123/SAPNet.

Despite its importance generating attacks for multi label learning (MLL) models has received much less attention compared to multi-class recognition. Attacking an MLL model by optimizing a loss on the target set of labels has often the undesired consequence of changing the predictions for other labels. On the other hand adding a loss on the remaining labels to keep them fixed leads to highly negatively correlated gradient directions reducing the attack effectiveness. In this paper we develop a framework for crafting effective and semantic aware adversarial attacks for MLL. First to obtain an attack that leads to semantically consistent predictions across all labels we find a minimal superset of the target labels referred to as consistent target set. To do so we develop an efficient search algorithm over a knowledge graph which encodes label dependencies. Next we propose an optimization that searches for an attack that modifies the predictions of labels in the consistent target set while ensuring other labels will not get affected. This leads to an efficient algorithm that projects the gradient of the consistent target set loss onto the orthogonal direction of the gradient of the loss on other labels. Our framework can generate attacks on different target set sizes and for MLL with thousands of labels (as in OpenImages). Finally by extensive experiments on three datasets and several MLL models we show that our method generates both successful and semantically consistent attacks.

In recent years there has been enormous interest in vision-language models trained using self-supervised objectives. However the use of large-scale datasets scraped from the web for training also makes these models vulnerable to potential security threats such as backdooring and poisoning attacks. In this paper we propose a method for mitigating such attacks on contrastively trained vision-language models. Our approach leverages external knowledge extracted from a language model to prevent models from learning correlations between image regions which lack strong alignment with external knowledge. We do this by imposing constraints to enforce that attention paid by the model to visual regions is proportional to the alignment of those regions with external knowledge. We conduct extensive experiments using a variety of recent backdooring and poisoning attacks on multiple datasets and architectures. Our results clearly demonstrate that our proposed approach is highly effective at defending against such attacks across multiple settings while maintaining model utility and without requiring any changes at inference time.

A novel algorithm called semantic line combination detector (SLCD) to find an optimal combination of semantic lines is proposed in this paper. It processes all lines in each line combination at once to assess the overall harmony of the lines. First we generate various line combinations from reliable lines. Second we estimate the score of each line combination and determine the best one. Experimental results demonstrate that the proposed SLCD outperforms existing semantic line detectors on various datasets. Moreover it is shown that SLCD can be applied effectively to three vision tasks of vanishing point detection symmetry axis detection and composition-based image retrieval. Our codes are available at https://github.com/Jinwon-Ko/SLCD.

The field of 3D detailed human mesh reconstruction has made significant progress in recent years. However current methods still face challenges when used in industrial applications due to unstable results low-quality meshes and a lack of UV unwrapping and skinning weights. In this paper we present SHERT a novel pipeline that can reconstruct semantic human meshes with textures and high-precision details. SHERT applies semantic- and normal-based sampling between the detailed surface (e.g. mesh and SDF) and the corresponding SMPL-X model to obtain a partially sampled semantic mesh and then generates the complete semantic mesh by our specifically designed self-supervised completion and refinement networks. Using the complete semantic mesh as a basis we employ a texture diffusion model to create human textures that are driven by both images and texts. Our reconstructed meshes have stable UV unwrapping high-quality triangle meshes and consistent semantic information. The given SMPL-X model provides semantic information and shape priors allowing SHERT to perform well even with incorrect and incomplete inputs. The semantic information also makes it easy to substitute and animate different body parts such as the face body and hands. Quantitative and qualitative experiments demonstrate that SHERT is capable of producing high-fidelity and robust semantic meshes that outperform state-of-the-art methods.

We present "SemCity" a 3D diffusion model for semantic scene generation in real-world outdoor environments. Most 3D diffusion models focus on generating a single object synthetic indoor scenes or synthetic outdoor scenes while the generation of real-world outdoor scenes is rarely addressed. In this paper we concentrate on generating a real-outdoor scene through learning a diffusion model on a real-world outdoor dataset. In contrast to synthetic data real-outdoor datasets often contain more empty spaces due to sensor limitations causing challenges in learning real-outdoor distributions. To address this issue we exploit a triplane representation as a proxy form of scene distributions to be learned by our diffusion model. Furthermore we propose a triplane manipulation that integrates seamlessly with our triplane diffusion model. The manipulation improves our diffusion model's applicability in a variety of downstream tasks related to outdoor scene generation such as scene inpainting scene outpainting and semantic scene completion refinements. In experimental results we demonstrate that our triplane diffusion model shows meaningful generation results compared with existing work in a real-outdoor dataset SemanticKITTI. We also show our triplane manipulation facilitates seamlessly adding removing or modifying objects within a scene. Further it also enables the expansion of scenes toward a city-level scale. Finally we evaluate our method on semantic scene completion refinements where our diffusion model enhances predictions of semantic scene completion networks by learning scene distribution. Our code is available at https://github.com/zoomin-lee/SemCity.

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.

3D occupancy prediction is an important task for the robustness of vision-centric autonomous driving which aims to predict whether each point is occupied in the surrounding 3D space. Existing methods usually require 3D occupancy labels to produce meaningful results. However it is very laborious to annotate the occupancy status of each voxel. In this paper we propose SelfOcc to explore a self-supervised way to learn 3D occupancy using only video sequences. We first transform the images into the 3D space (e.g. bird's eye view) to obtain 3D representation of the scene. We directly impose constraints on the 3D representations by treating them as signed distance fields. We can then render 2D images of previous and future frames as self-supervision signals to learn the 3D representations. We propose an MVS-embedded strategy to directly optimize the SDF-induced weights with multiple depth proposals. Our SelfOcc outperforms the previous best method SceneRF by 58.7% using a single frame as input on SemanticKITTI and is the first self-supervised work that produces reasonable 3D occupancy for surround cameras on nuScenes. SelfOcc produces high-quality depth and achieves state-of-the-art results on novel depth synthesis monocular depth estimation and surround-view depth estimation on the SemanticKITTI KITTI-2015 and nuScenes respectively. Code: https://github.com/huang-yh/SelfOcc.

Spurious correlations can cause strong biases in deep neural networks impairing generalization ability. While most existing debiasing methods require full supervision on either spurious attributes or target labels training a debiased model from a limited amount of both annotations is still an open question. To address this issue we investigate an interesting phenomenon using the spectral analysis of latent representations: spuriously correlated attributes make neural networks inductively biased towards encoding lower effective rank representations. We also show that a rank regularization can amplify this bias in a way that encourages highly correlated features. Leveraging these findings we propose a self-supervised debiasing framework potentially compatible with unlabeled samples. Specifically we first pretrain a biased encoder in a self-supervised manner with the rank regularization serving as a semantic bottleneck to enforce the encoder to learn the spuriously correlated attributes. This biased encoder is then used to discover and upweight bias-conflicting samples in a downstream task serving as a boosting to effectively debias the main model. Remarkably the proposed debiasing framework significantly improves the generalization performance of self-supervised learning baselines and in some cases even outperforms state-of-the-art supervised debiasing approaches.

Text-to-image generation has witnessed significant progress with the advent of diffusion models. Despite the ability to generate photorealistic images current text-to-image diffusion models still often struggle to accurately interpret and follow complex input text prompts. In contrast to existing models that aim to generate images only with their best effort we introduce Self-correcting LLM-controlled Diffusion (SLD). SLD is a framework that generates an image from the input prompt assesses its alignment with the prompt and performs self-corrections on the inaccuracies in the generated image. Steered by an LLM controller SLD turns text-to-image generation into an iterative closed-loop process ensuring correctness in the resulting image. SLD is not only training-free but can also be seamlessly integrated with diffusion models behind API access such as DALL-E 3 to further boost the performance of state-of-the-art diffusion models. Experimental results show that our approach can rectify a majority of incorrect generations particularly in generative numeracy attribute binding and spatial relationships. Furthermore by simply adjusting the instructions to the LLM SLD can perform image editing tasks bridging the gap between text-to-image generation and image editing pipelines. Our code is available at: https://self-correcting-llm-diffusion.github.io.

Visual program synthesis is a promising approach to exploit the reasoning abilities of large language models for compositional computer vision tasks. Previous work has used few-shot prompting with frozen LLMs to synthesize visual programs. Training an LLM to write better visual programs is an attractive prospect but it is unclear how to accomplish this. No dataset of visual programs for training exists and acquisition of a visual program dataset cannot be easily crowdsourced due to the need for expert annotators. To get around the lack of direct supervision we explore improving the program synthesis abilities of an LLM using feedback from interactive experience. We propose a method where we exploit existing annotations for a vision-language task to improvise a coarse reward signal for that task treat the LLM as a policy and apply reinforced self-training to improve the visual program synthesis ability of the LLM for that task. We describe a series of experiments on object detection compositional visual question answering and image-text retrieval and show that in each case the self-trained LLM outperforms or performs on par with few-shot frozen LLMs that are an order of magnitude larger. Website: https://zaidkhan.me/ViReP

Current self-supervised methods can primarily be categorized into contrastive learning and masked image modeling. Extensive studies have demonstrated that combining these two approaches can achieve state-of-the-art performance. However these methods essentially reinforce the global consistency of contrastive learning without taking into account the conflicts between these two approaches which hinders their generalizability to arbitrary scenarios. In this paper we theoretically prove that MAE serves as a patch-level contrastive learning where each patch within an image is considered as a distinct category. This presents a significant conflict with global-level contrastive learning which treats all patches in an image as an identical category. To address this conflict this work abandons the non-generalizable global-level constraints and proposes explicit patch-level contrastive learning as a solution. Specifically this work employs the encoder of MAE to generate dual-branch features which then perform patch-level learning through a decoder. In contrast to global-level data augmentation in contrastive learning our approach leverages patch-level feature augmentation to mitigate interference from global-level learning. Consequently our approach can learn heterogeneous representations from a single image while avoiding the conflicts encountered by previous methods. Massive experiments affirm the potential of our method for learning from arbitrary scenarios.

In this paper we propose a novel concept of path consistency to learn robust object matching without using manual object identity supervision. Our key idea is that to track a object through frames we can obtain multiple different association results from a model by varying the frames it can observe i.e. skipping frames in observation. As the differences in observations do not alter the identities of objects the obtained association results should be consistent. Based on this rationale we generate multiple observation paths each specifying a different set of frames to be skipped and formulate the Path Consistency Loss that enforces the association results are consistent across different observation paths. We use the proposed loss to train our object matching model with only self-supervision. By extensive experiments on three tracking datasets (MOT17 PersonPath22 KITTI) we demonstrate that our method outperforms existing unsupervised methods with consistent margins on various evaluation metrics and even achieves performance close to supervised methods.

Self-supervised pre-training has been proved to be effective in learning transferable representations that benefit various visual tasks. This paper asks this question: can self-supervised pre-training learn general facial representations for various facial analysis tasks? Recent efforts toward this goal are limited to treating each face image as a whole i.e. learning consistent facial representations at the image-level which overlooks the consistency of local facial representations (i.e. facial regions like eyes nose etc). In this work we make a first attempt to propose a novel self-supervised facial representation learning framework to learn consistent global and local facial representations Facial Region Awareness (FRA). Specifically we explicitly enforce the consistency of facial regions by matching the local facial representations across views which are extracted with learned heatmaps highlighting the facial regions. Inspired by the mask prediction in supervised semantic segmentation we obtain the heatmaps via cosine similarity between the per-pixel projection of feature maps and facial mask embeddings computed from learnable positional embeddings which leverage the attention mechanism to globally look up the facial image for facial regions. To learn such heatmaps we formulate the learning of facial mask embeddings as a deep clustering problem by assigning the pixel features from the feature maps to them. The transfer learning results on facial classification and regression tasks show that our FRA outperforms previous pre-trained models and more importantly using ResNet as the unified backbone for various tasks our FRA achieves comparable or even better performance compared with SOTA methods in facial analysis tasks.

Learning-based isosurface extraction methods have recently emerged as a robust and efficient alternative to axiomatic techniques. However the vast majority of such approaches rely on supervised training with axiomatically computed ground truths thus potentially inheriting biases and data artefacts of the corresponding axiomatic methods. Steering away from such dependencies we propose a self-supervised training scheme to the Neural Dual Contouring meshing framework resulting in our method: Self-Supervised Dual Contouring (SDC). Instead of optimizing predicted mesh vertices with supervised training we use two novel self-supervised loss functions that encourage the consistency between distances to the generated mesh up to the first order. Meshes reconstructed by SDC surpass existing data-driven methods in capturing intricate details while being more robust to possible irregularities in the input. Furthermore we use the same self-supervised training objective linking inferred mesh and input SDF to regularize the training process of Deep Implicit Networks (DINs). We demonstrate that the resulting DINs produce higher-quality implicit functions ultimately leading to more accurate and detail-preserving surfaces compared to prior baselines for different input modalities. Finally we demonstrate that our self-supervised losses improve meshing performance in the single-view reconstruction task by enabling joint training of predicted SDF and resulting output mesh.