Existing score distillation methods are sensitive to classifier-free guidance (CFG) scale manifested as over-smoothness or instability at small CFG scales while over-saturation at large ones. To explain and analyze these issues we revisit the derivation of Score Distillation Sampling (SDS) and decipher existing score distillation with the Wasserstein Generative Adversarial Network (WGAN) paradigm. With the WGAN paradigm we find that existing score distillation either employs a fixed sub-optimal discriminator or conducts incomplete discriminator optimization resulting in the scale-sensitive issue. We propose the Adversarial Score Distillation (ASD) which maintains an optimizable discriminator and updates it using the complete optimization objective. Experiments show that the proposed ASD performs favorably in 2D distillation and text-to-3D tasks against existing methods. Furthermore to explore the generalization ability of our paradigm we extend ASD to the image editing task which achieves competitive results. The project page and code are at https://github.com/2y7c3/ASD
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Video summarization aims to generate a concise representation of a video capturing its essential content and key moments while reducing its overall length. Although several methods employ attention mechanisms to handle long-term dependencies they often fail to capture the visual significance inherent in frames. To address this limitation we propose a CNN-based SpatioTemporal Attention (CSTA) method that stacks each feature of frames from a single video to form image-like frame representations and applies 2D CNN to these frame features. Our methodology relies on CNN to comprehend the inter and intra-frame relations and to find crucial attributes in videos by exploiting its ability to learn absolute positions within images. In contrast to previous work compromising efficiency by designing additional modules to focus on spatial importance CSTA requires minimal computational overhead as it uses CNN as a sliding window. Extensive experiments on two benchmark datasets (SumMe and TVSum) demonstrate that our proposed approach achieves state-of-the-art performance with fewer MACs compared to previous methods. Codes are available at https://github.com/thswodnjs3/CSTA.
Due to the omnipresence of Neural Radiance Fields (NeRFs) the interest towards editable implicit 3D representations has surged over the last years. However editing implicit or hybrid representations as used for NeRFs is difficult due to the entanglement of appearance and geometry encoded in the model parameters. Despite these challenges recent research has shown first promising steps towards photorealistic and non-photorealistic appearance edits. The main open issues of related work include limited interactivity a lack of support for local edits and large memory requirements rendering them less useful in practice. We address these limitations with LAENeRF a unified framework for photorealistic and non-photorealistic appearance editing of NeRFs. To tackle local editing we leverage a voxel grid as starting point for region selection. We learn a mapping from expected ray terminations to final output color which can optionally be supervised by a style loss resulting in a framework which can perform photorealistic and non-photorealistic appearance editing of selected regions. Relying on a single point per ray for our mapping we limit memory requirements and enable fast optimization. To guarantee interactivity we compose the output color using a set of learned modifiable base colors composed with additive layer mixing. Compared to concurrent work LAENeRF enables recoloring and stylization while keeping processing time low. Furthermore we demonstrate that our approach surpasses baseline methods both quantitatively and qualitatively.
Image deblurring aims to remove undesired blurs from an image captured in a dynamic scene. Much research has been dedicated to improving deblurring performance through model architectural designs. However there is little work on data augmentation for image deblurring. Since continuous motion causes blurred artifacts during image exposure we aspire to develop a groundbreaking blur augmentation method to generate diverse blurred images by simulating motion trajectories in a continuous space. This paper proposes Implicit Diffusion-based reBLurring AUgmentation (ID-Blau) utilizing a sharp image paired with a controllable blur condition map to produce a corresponding blurred image. We parameterize the blur patterns of a blurred image with their orientations and magnitudes as a pixel-wise blur condition map to simulate motion trajectories and implicitly represent them in a continuous space. By sampling diverse blur conditions ID-Blau can generate various blurred images unseen in the training set. Experimental results demonstrate that ID-Blau can produce realistic blurred images for training and thus significantly improve performance for state-of-the-art deblurring models. The source code is available at https://github.com/plusgood-steven/ID-Blau.
Deep Single Image Camera Calibration by Heatmap Regression to Recover Fisheye Images Under Manhattan World Assumption
PDF ↗A Manhattan world lying along cuboid buildings is useful for camera angle estimation. However accurate and robust angle estimation from fisheye images in the Manhattan world has remained an open challenge because general scene images tend to lack constraints such as lines arcs and vanishing points. To achieve higher accuracy and robustness we propose a learning-based calibration method that uses heatmap regression which is similar to pose estimation using keypoints to detect the directions of labeled image coordinates. Simultaneously our two estimators recover the rotation and remove fisheye distortion by remapping from a general scene image. Without considering vanishing-point constraints we find that additional points for learning-based methods can be defined. To compensate for the lack of vanishing points in images we introduce auxiliary diagonal points that have the optimal 3D arrangement of spatial uniformity. Extensive experiments demonstrated that our method outperforms conventional methods on large-scale datasets and with off-the-shelf cameras.
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.
Foundation segmentation models while powerful pose a significant risk: they enable users to effortlessly extract any objects from any digital content with a single click potentially leading to copyright infringement or malicious misuse. To mitigate this risk we introduce a new task "Anything Unsegmentable" to grant any image "the right to be unsegmented". The ambitious pursuit of the task is to achieve highly transferable adversarial attack against all prompt-based segmentation models regardless of model parameterizations and prompts. We highlight the non-transferable and heterogeneous nature of prompt-specific adversarial noises. Our approach focuses on disrupting image encoder features to achieve prompt-agnostic attacks. Intriguingly targeted feature attacks exhibit better transferability compared to untargeted ones suggesting the optimal update direction aligns with the image manifold. Based on the observations we design a novel attack named Unsegment Anything by Simulating Deformation (UAD). Our attack optimizes a differentiable deformation function to create a target deformed image which alters structural information while preserving achievable feature distance by adversarial example. Extensive experiments verify the effectiveness of our approach compromising a variety of promptable segmentation models with different architectures and prompt interfaces.
Bokeh is widely used in photography to draw attention to the subject while effectively isolating distractions in the background. Computational methods can simulate bokeh effects without relying on a physical camera lens but the inaccurate lens modeling in existing filtering-based methods leads to artifacts that need post-processing or learning-based methods to fix. We propose Dr.Bokeh a novel rendering method that addresses the issue by directly correcting the defect that violates the physics in the current filtering-based bokeh rendering equation. Dr.Bokeh first preprocesses the input RGBD to obtain a layered scene representation. Dr.Bokeh then takes the layered representation and user-defined lens parameters to render photo-realistic lens blur based on the novel occlusion-aware bokeh rendering method. Experiments show that the non-learning based renderer Dr.Bokeh outperforms state-of-the-art bokeh rendering algorithms in terms of photo-realism. In addition extensive quantitative and qualitative evaluations show the more accurate lens model further pushes the limit of a closely related field depth-from-defocus.
Boosting Order-Preserving and Transferability for Neural Architecture Search: a Joint Architecture Refined Search and Fine-tuning Approach
PDF ↗Supernet is a core component in many recent Neural Architecture Search (NAS) methods. It not only helps embody the search space but also provides a (relative) estimation of the final performance of candidate architectures. Thus it is critical that the top architectures ranked by a supernet should be consistent with those ranked by true performance which is known as the order-preserving ability. In this work we analyze the order-preserving ability on the whole search space (global) and a sub-space of top architectures (local) and empirically show that the local order-preserving for current two-stage NAS methods still need to be improved. To rectify this we propose a novel concept of Supernet Shifting a refined search strategy combining architecture searching with supernet fine-tuning. Specifically apart from evaluating the training loss is also accumulated in searching and the supernet is updated every iteration. Since superior architectures are sampled more frequently in evolutionary searching the supernet is encouraged to focus on top architectures thus improving local order-preserving. Besides a pre-trained supernet is often un-reusable for one-shot methods. We show that Supernet Shifting can fulfill transferring supernet to a new dataset. Specifically the last classifier layer will be unset and trained through evolutionary searching. Comprehensive experiments show that our method has better order-preserving ability and can find a dominating architecture. Moreover the pre-trained supernet can be easily transferred into a new dataset with no loss of performance.
Multiscale Vision Transformers Meet Bipartite Matching for Efficient Single-stage Action Localization
PDF ↗Action Localization is a challenging problem that combines detection and recognition tasks which are often addressed separately. State-of-the-art methods rely on off-the-shelf bounding box detections pre-computed at high resolution and propose transformer models that focus on the classification task alone. Such two-stage solutions are prohibitive for real-time deployment. On the other hand single-stage methods target both tasks by devoting part of the network (generally the backbone) to sharing the majority of the workload compromising performance for speed. These methods build on adding a DETR head with learnable queries that after cross- and self-attention can be sent to corresponding MLPs for detecting a person's bounding box and action. However DETR-like architectures are challenging to train and can incur in big complexity. In this paper we observe that a straight bipartite matching loss can be applied to the output tokens of a vision transformer. This results in a backbone + MLP architecture that can do both tasks without the need of an extra encoder-decoder head and learnable queries. We show that a single MViTv2-S architecture trained with bipartite matching to perform both tasks surpasses the same MViTv2-S when trained with RoI align on pre-computed bounding boxes. With a careful design of token pooling and the proposed training pipeline our Bipartite-Matching Vision Transformer model BMViT achieves +3 mAP on AVA2.2. w.r.t. the two-stage MViTv2-S counterpart. Code is available at https://github.com/IoannaNti/BMViT
Video deblurring aims to restore sharp frames from blurred video clips. Despite notable progress in video deblurring works it is still a challenging problem because of the loss of motion information during the duration of the exposure time. Since event cameras can capture clear motion information asynchronously with high temporal resolution several works exploit the event camera for deblurring as they can provide abundant motion information. However despite these approaches there were few cases of actively exploiting the long-range temporal dependency of videos. To tackle these deficiencies we present an event-based video deblurring framework by actively utilizing temporal information from videos. To be specific we first introduce a frequency-based cross-modal feature enhancement module. Second we propose event-guided video alignment modules by considering the valuable characteristics of the event and videos. In addition we designed a hybrid camera system to collect the first real-world event-based video deblurring dataset. For the first time we build a dataset containing synchronized high-resolution real-world blurred videos and corresponding sharp videos and event streams. Experimental results validate that our frameworks significantly outperform the state-of-the-art frame-based and event-based deblurring works in the various datasets. In addition we designed a hybrid camera system to collect the first real-world event-based video deblurring dataset. For the first time we build a dataset containing synchronized high-resolution real-world blurred videos and corresponding sharp videos and event streams. Experimental results validate that our frameworks significantly outperform the state-of-the-art frame-based and event-based deblurring works in the various datasets. The project pages are available at https://sites.google.com/view/fevd-cvpr2024.
Place Recognition is crucial for unmanned vehicles in terms of localization and mapping. Recent years have witnessed numerous explorations in the field where 2D cameras and 3D LiDARs are mostly employed. Despite their admirable performance they may encounter challenges in adverse weather such as rain and fog. Hopefully 4D millimeter-wave Radar emerges as a promising alternative as its longer wavelength makes it virtually immune to interference from tiny particles of fog and rain. Therefore in this work we propose a novel 4D Radar place recognition model TransLoc4D based on sparse convolution and Transformer structures. Specifically a Minkloc4D backbone is first proposed to leverage the geometric intensity and velocity information from 4D Radar scans. While mainstream 3D LiDAR solutions merely capture geometric structures of point clouds Minkloc4D explores the intensity and velocity properties of 4D Radar scans and demonstrates their effectiveness. After feature extraction a Transformer layer is introduced to enhance local features where linear self-attention captures the long-range dependency of point cloud alleviating its sparsity and noise. To validate TransLoc4D we construct two datasets and set up benchmarks for 4D radar place recognition. Experiments show TransLoc4D is feasible and can robustly deal with dynamic and adverse environments.
Humans possess the capability to comprehend diverse modalities and seamlessly transfer information between them. In this work we introduce ModaVerse a Multi-modal Large Language Model (MLLM) capable of comprehending and transforming content across various modalities including images videos and audio. Predominant MLLM frameworks have largely relied on aligning latent spaces of textual and non-textual features. This alignment process which synchronizes a language model trained on textual data with encoders and decoders trained on multi-modal data often necessitates extensive training of several projection layers in multiple stages. Inspired by LLM-as-agent methodologies we propose a novel Input/Output (I/O) alignment mechanism that operates directly at the level of natural language. It aligns the LLM's output with the input of generative models avoiding the complexities associated with latent feature alignments and simplifying the multiple training stages of existing MLLMs into a single efficient process. By conducting experiments on several benchmarks we demonstrate that our approach attains comparable performance with the state of the art while achieving considerable efficiencies in data usage.
Although polygon meshes have been a standard representation in geometry processing their irregular and combinatorial nature hinders their suitability for learning-based applications. In this work we introduce a novel learnable mesh representation through a set of local 3D sample Points and their associated Normals and Quadric error metrics (QEM) w.r.t. the underlying shape which we denote PoNQ. A global mesh is directly derived from PoNQ by efficiently leveraging the knowledge of the local quadric errors. Besides marking the first use of QEM within a neural shape representation our contribution guarantees both topological and geometrical properties by ensuring that a PoNQ mesh does not self-intersect and is always the boundary of a volume. Notably our representation does not rely on a regular grid is supervised directly by the target surface alone and also handles open surfaces with boundaries and/or sharp features. We demonstrate the efficacy of PoNQ through a learning-based mesh prediction from SDF grids and show that our method surpasses recent state-of-the-art techniques in terms of both surface and edge-based metrics.
Partial-label learning (PLL) is an important weakly supervised learning problem which allows each training example to have a candidate label set instead of a single ground-truth label. Identification-based methods have been widely explored to tackle label ambiguity issues in PLL which regard the true label as a latent variable to be identified. However identifying the true labels accurately and completely remains challenging causing noise in pseudo labels during model training. In this paper we propose a new method called CroSel which leverages historical predictions from the model to identify true labels for most training examples. First we introduce a cross selection strategy which enables two deep models to select true labels of partially labeled data for each other. Besides we propose a novel consistency regularization term called co-mix to avoid sample waste and tiny noise caused by false selection. In this way CroSel can pick out the true labels of most examples with high precision. Extensive experiments demonstrate the superiority of CroSel which consistently outperforms previous state-of-the-art methods on benchmark datasets. Additionally our method achieves over 90% accuracy and quantity for selecting true labels on CIFAR-type datasets under various settings.
Wavelet-based Fourier Information Interaction with Frequency Diffusion Adjustment for Underwater Image Restoration
PDF ↗Underwater images are subject to intricate and diverse degradation inevitably affecting the effectiveness of underwater visual tasks. However most approaches primarily operate in the raw pixel space of images which limits the exploration of the frequency characteristics of underwater images leading to an inadequate utilization of deep models' representational capabilities in producing high-quality images. In this paper we introduce a novel Underwater Image Enhancement (UIE) framework named WF-Diff designed to fully leverage the characteristics of frequency domain information and diffusion models. WF-Diff consists of two detachable networks: Wavelet-based Fourier information interaction network (WFI2-net) and Frequency Residual Diffusion Adjustment Module (FRDAM). With our full exploration of the frequency domain information WFI2-net aims to achieve preliminary enhancement of frequency information in the wavelet space. Our proposed FRDAM can further refine the high- and low-frequency information of the initial enhanced images which can be viewed as a plug-and-play universal module to adjust the detail of the underwater images. With the above techniques our algorithm can show SOTA performance on real-world underwater image datasets and achieves competitive performance in visual quality.
Recent advancements in Vision-Language Models (VLMs) have marked a significant leap in bridging the gap between computer vision and natural language processing. However traditional VLMs trained through contrastive learning on limited and noisy image-text pairs often lack the spatial and linguistic understanding to generalize well to dense vision tasks or less common languages. Our approach Solid Foundation CLIP (SF-CLIP) circumvents this issue by implicitly building on the solid visual and language understanding of foundational models trained on vast amounts of unimodal data. SF-CLIP integrates contrastive image-text pretraining with a masked knowledge distillation from large foundational text and vision models. This methodology guides our VLM in developing robust text and image representations. As a result SF-CLIP shows exceptional zero-shot classification accuracy and enhanced image and text retrieval capabilities setting a new state of the art for ViT-B/16 trained on YFCC15M and CC12M. Moreover the dense per-patch supervision enhances our zero-shot and linear probe performance in semantic segmentation tasks. A remarkable aspect of our model is its multilingual proficiency evidenced by strong retrieval results in multiple languages despite being trained predominantly on English data. We achieve all of these improvements without sacrificing the training efficiency through our selective application of masked distillation and the inheritance of teacher word embeddings.
Semantic segmentation models while effective for in-distribution categories face challenges in real-world deployment due to encountering out-of-distribution (OoD) objects. Detecting these OoD objects is crucial for safety-critical applications. Existing methods rely on anomaly scores but choosing a suitable threshold for generating masks presents difficulties and can lead to fragmentation and inaccuracy. This paper introduces a method to convert anomaly Score To segmentation Mask called S2M a simple and effective framework for OoD detection in semantic segmentation. Unlike assigning anomaly scores to pixels S2M directly segments the entire OoD object. By transforming anomaly scores into prompts for a promptable segmentation model S2M eliminates the need for threshold selection. Extensive experiments demonstrate that S2M outperforms the state-of-the-art by approximately 20% in IoU and 40% in mean F1 score on average across various benchmarks including Fishyscapes Segment-Me-If-You-Can and RoadAnomaly datasets.
For human-centric large-scale scenes fine-grained modeling for 3D human global pose and shape is significant for scene understanding and can benefit many real-world applications. In this paper we present LiveHPS a novel single-LiDAR-based approach for scene-level human pose and shape estimation without any limitation of light conditions and wearable devices. In particular we design a distillation mechanism to mitigate the distribution-varying effect of LiDAR point clouds and exploit the temporal-spatial geometric and dynamic information existing in consecutive frames to solve the occlusion and noise disturbance. LiveHPS with its efficient configuration and high-quality output is well-suited for real-world applications. Moreover we propose a huge human motion dataset named FreeMotion which is collected in various scenarios with diverse human poses shapes and translations. It consists of multi-modal and multi-view acquisition data from calibrated and synchronized LiDARs cameras and IMUs. Extensive experiments on our new dataset and other public datasets demonstrate the SOTA performance and robustness of our approach. We will release our code and dataset soon.
SPOT: Self-Training with Patch-Order Permutation for Object-Centric Learning with Autoregressive Transformers
PDF ↗Unsupervised object-centric learning aims to decompose scenes into interpretable object entities termed slots. Slot-based auto-encoders stand out as a prominent method for this task. Within them crucial aspects include guiding the encoder to generate object-specific slots and ensuring the decoder utilizes them during reconstruction. This work introduces two novel techniques (i) an attention-based self-training approach which distills superior slot-based attention masks from the decoder to the encoder enhancing object segmentation and (ii) an innovative patch-order permutation strategy for autoregressive transformers that strengthens the role of slot vectors in reconstruction. The effectiveness of these strategies is showcased experimentally. The combined approach significantly surpasses prior slot-based autoencoder methods in unsupervised object segmentation especially with complex real-world images. We provide the implementation code at https://github.com/gkakogeorgiou/spot .