CVPR 2024 Papers

Event cameras characterized by high temporal resolution high dynamic range low power consumption and high pixel bandwidth offer unique capabilities for object detection in specialized contexts. Despite these advantages the inherent sparsity and asynchrony of event data pose challenges to existing object detection algorithms. Spiking Neural Networks (SNNs) inspired by the way the human brain codes and processes information offer a potential solution to these difficulties. However their performance in object detection using event cameras is limited in current implementations. In this paper we propose the Spiking Fusion Object Detector (SFOD) a simple and efficient approach to SNN-based object detection. Specifically we design a Spiking Fusion Module achieving the first-time fusion of feature maps from different scales in SNNs applied to event cameras. Additionally through integrating our analysis and experiments conducted during the pretraining of the backbone network on the NCAR dataset we delve deeply into the impact of spiking decoding strategies and loss functions on model performance. Thereby we establish state-of-the-art classification results based on SNNs achieving 93.7% accuracy on the NCAR dataset. Experimental results on the GEN1 detection dataset demonstrate that the SFOD achieves a state-of-the-art mAP of 32.1% outperforming existing SNN-based approaches. Our research not only underscores the potential of SNNs in object detection with event cameras but also propels the advancement of SNNs. Code is available at https://github.com/yimeng-fan/SFOD.

Multimodal large language models (MLLMs) building upon the foundation of powerful large language models (LLMs) have recently demonstrated exceptional capabilities in generating not only texts but also images given interleaved multimodal inputs (acting like a combination of GPT-4V and DALL-E 3). However existing MLLM benchmarks remain limited to assessing only models' comprehension ability of single image-text inputs failing to keep up with the strides made in MLLMs. A comprehensive benchmark is imperative for investigating the progress and uncovering the limitations of current MLLMs. In this work we categorize the capabilities of MLLMs into hierarchical levels from L_0 to L_4 based on the modalities they can accept and generate and propose SEED-Bench a comprehensive benchmark that evaluates the hierarchical capabilities of MLLMs. Specifically SEED-Bench comprises 24K multiple-choice questions with accurate human annotations which spans 27 dimensions including the evaluation of both text and image generation. Multiple-choice questions with groundtruth options derived from human annotation enables an objective and efficient assessment of model performance eliminating the need for human or GPT intervention during evaluation. We further evaluate the performance of 22 prominent open-source MLLMs and summarize valuable observations. By revealing the limitations of existing MLLMs through extensive evaluations we aim for SEED-Bench to provide insights that will motivate future research towards the goal of General Artificial Intelligence.

Open-vocabulary semantic segmentation strives to distinguish pixels into different semantic groups from an open set of categories. Most existing methods explore utilizing pre-trained vision-language models in which the key is to adopt the image-level model for pixel-level segmentation task. In this paper we propose a simple encoder-decoder named SED for open-vocabulary semantic segmentation which comprises a hierarchical encoder-based cost map generation and a gradual fusion decoder with category early rejection. The hierarchical encoder-based cost map generation employs hierarchical backbone instead of plain transformer to predict pixel-level image-text cost map. Compared to plain transformer hierarchical backbone better captures local spatial information and has linear computational complexity with respect to input size. Our gradual fusion decoder employs a top-down structure to combine cost map and the feature maps of different backbone levels for segmentation. To accelerate inference speed we introduce a category early rejection scheme in the decoder that rejects many no-existing categories at the early layer of decoder resulting in at most 4.7 times acceleration without accuracy degradation. Experiments are performed on multiple open-vocabulary semantic segmentation datasets which demonstrates the efficacy of our SED method. When using ConvNeXt-B our SED method achieves mIoU score of 31.6% on ADE20K with 150 categories at 82 millisecond (ms) per image on a single A6000. Our source code is available at https://github.com/xb534/SED.

We introduce SEAS using ShapE-Aligned Supervision to enhance appearance-based person re-identification. When recognizing an individual's identity existing methods primarily rely on appearance which can be influenced by the background environment due to a lack of body shape awareness. Although some methods attempt to incorporate other modalities such as gait or body shape they encode the additional modality separately resulting in extra computational costs and lacking an inherent connection with appearance. In this paper we explore the use of implicit 3-D body shape representations as pixel-level guidance to augment the extraction of identity features with body shape knowledge in addition to appearance. Using body shape as supervision rather than as input provides shape-aware enhancements without any increase in computational cost and delivers coherent integration with pixel-wise appearance features. Moreover for video-based person re-identification we align pixel-level features across frames with shape awareness to ensure temporal consistency. Our results demonstrate that incorporating body shape as pixel-level supervision reduces rank-1 errors by 1.4% for frame-based and by 2.5% for video-based re-identification tasks respectively and can also be generalized to other existing appearance-based person re-identification methods.

Multimodal Visual Object Tracking (VOT) has recently gained significant attention due to its robustness. Early research focused on fully fine-tuning RGB-based trackers which was inefficient and lacked generalized representation due to the scarcity of multimodal data. Therefore recent studies have utilized prompt tuning to transfer pre-trained RGB-based trackers to multimodal data. However the modality gap limits pre-trained knowledge recall and the dominance of the RGB modality persists preventing the full utilization of information from other modalities. To address these issues we propose a novel symmetric multimodal tracking framework called SDSTrack. We introduce lightweight adaptation for efficient fine-tuning which directly transfers the feature extraction ability from RGB to other domains with a small number of trainable parameters and integrates multimodal features in a balanced symmetric manner. Furthermore we design a complementary masked patch distillation strategy to enhance the robustness of trackers in complex environments such as extreme weather poor imaging and sensor failure. Extensive experiments demonstrate that SDSTrack outperforms state-of-the-art methods in various multimodal tracking scenarios including RGB+Depth RGB+Thermal and RGB+Event tracking and exhibits impressive results in extreme conditions. Our source code is available at : https://github.com/hoqolo/SDSTrack.

Recently transformer-based methods have achieved state-of-the-art prediction quality on human pose estimation(HPE). Nonetheless most of these top-performing transformer-based models are too computation-consuming and storage-demanding to deploy on edge computing platforms. Those transformer-based models that require fewer resources are prone to under-fitting due to their smaller scale and thus perform notably worse than their larger counterparts. Given this conundrum we introduce SDPose a new self-distillation method for improving the performance of small transformer-based models. To mitigate the problem of under-fitting we design a transformer module named Multi-Cycled Transformer(MCT) based on multiple-cycled forwards to more fully exploit the potential of small model parameters. Further in order to prevent the additional inference compute-consuming brought by MCT we introduce a self-distillation scheme extracting the knowledge from the MCT module to a naive forward model. Specifically on the MSCOCO validation dataset SDPose-T obtains 69.7% mAP with 4.4M parameters and 1.8 GFLOPs. Furthermore SDPose-S-V2 obtains 73.5% mAP on the MSCOCO validation dataset with 6.2M parameters and 4.7 GFLOPs achieving a new state-of-the-art among predominant tiny neural network methods.

In this paper we address the challenge of matching semantically similar keypoints across image pairs. Existing research indicates that the intermediate output of the UNet within the Stable Diffusion (SD) can serve as robust image feature maps for such a matching task. We demonstrate that by employing a basic prompt tuning technique the inherent potential of Stable Diffusion can be harnessed resulting in a significant enhancement in accuracy over previous approaches. We further introduce a novel conditional prompting module that conditions the prompt on the local details of the input image pairs leading to a further improvement in performance. We designate our approach as SD4Match short for Stable Diffusion for Semantic Matching. Comprehensive evaluations of SD4Match on the PF-Pascal PF-Willow and SPair-71k datasets show that it sets new benchmarks in accuracy across all these datasets. Particularly SD4Match outperforms the previous state-of-the-art by a margin of 12 percentage points on the challenging SPair-71k dataset. Code is available at the project website: https://sd4match.active.vision.

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.

Diffusion Transformer (DiT) has emerged as the new trend of generative diffusion models on image generation. In view of extremely slow convergence in typical DiT recent breakthroughs have been driven by mask strategy that significantly improves the training efficiency of DiT with additional intra-image contextual learning. Despite this progress mask strategy still suffers from two inherent limitations: (a) training-inference discrepancy and (b) fuzzy relations between mask reconstruction & generative diffusion process resulting in sub-optimal training of DiT. In this work we address these limitations by novelly unleashing the self-supervised discrimination knowledge to boost DiT training. Technically we frame our DiT in a teacher-student manner. The teacher-student discriminative pairs are built on the diffusion noises along the same Probability Flow Ordinary Differential Equation (PF-ODE). Instead of applying mask reconstruction loss over both DiT encoder and decoder we decouple DiT encoder and decoder to separately tackle discriminative and generative objectives. In particular by encoding discriminative pairs with student and teacher DiT encoders a new discriminative loss is designed to encourage the inter-image alignment in the self-supervised embedding space. After that student samples are fed into student DiT decoder to perform the typical generative diffusion task. Extensive experiments are conducted on ImageNet dataset and our method achieves a competitive balance between training cost and generative capacity.

Accurate representation in media is known to improve the well-being of the people who consume it. Generative image models trained on large web-crawled datasets such as LAION are known to produce images with harmful stereotypes and misrepresentations of cultures. We improve inclusive representation in generated images by (1) engaging with communities to collect a culturally representative dataset that we call the Cross-Cultural Understanding Benchmark (CCUB) and (2) proposing a novel Self-Contrastive Fine-Tuning (SCoFT pronounced /soft/) method that leverages the model's known biases to self-improve. SCoFT is designed to prevent overfitting on small datasets encode only high-level information from the data and shift the generated distribution away from misrepresentations encoded in a pretrained model. Our user study conducted on 51 participants from 5 different countries based on their self-selected national cultural affiliation shows that fine-tuning on CCUB consistently generates images with higher cultural relevance and fewer stereotypes when compared to the Stable Diffusion baseline which is further improved with our SCoFT technique.

We present SCULPT a novel 3D generative model for clothed and textured 3D meshes of humans. Specifically we devise a deep neural network that learns to represent the geometry and appearance distribution of clothed human bodies. Training such a model is challenging as datasets of textured 3D meshes for humans are limited in size and accessibility. Our key observation is that there exist medium-sized 3D scan datasets like CAPE as well as large-scale 2D image datasets of clothed humans and multiple appearances can be mapped to a single geometry. To effectively learn from the two data modalities we propose an unpaired learning procedure for pose-dependent clothed and textured human meshes. Specifically we learn a pose-dependent geometry space from 3D scan data. We represent this as per vertex displacements w.r.t. the SMPL model. Next we train a geometry conditioned texture generator in an unsupervised way using the 2D image data. We use intermediate activations of the learned geometry model to condition our texture generator. To alleviate entanglement between pose and clothing type and pose and clothing appearance we condition both the texture and geometry generators with attribute labels such as clothing types for the geometry and clothing colors for the texture generator. We automatically generated these conditioning labels for the 2D images based on the visual question-answering model BLIP and CLIP. We validate our method on the SCULPT dataset and compare to state-of-the-art 3D generative models for clothed human bodies. Our code and data can be found at https://sculpt.is.tue.mpg.de.

Self-supervised landmark estimation is a challenging task that demands the formation of locally distinct feature representations to identify sparse facial landmarks in the absence of annotated data. To tackle this task existing state-of-the-art (SOTA) methods (1) extract coarse features from backbones that are trained with instance-level self-supervised learning (SSL) paradigms which neglect the dense prediction nature of the task (2) aggregate them into memory-intensive hypercolumn formations and (3) supervise lightweight projector networks to naively establish full local correspondences among all pairs of spatial features. In this paper we introduce SCE-MAE a framework that (1) leverages the MAE [??] a region-level SSL method that naturally better suits the landmark prediction task (2) operates on the vanilla feature map instead of on expensive hypercolumns and (3) employs a Correspondence Approximation and Refinement Block (CARB) that utilizes a simple density peak clustering algorithm and our proposed Locality-Constrained Repellence Loss to directly hone only select local correspondences. We demonstrate through extensive experiments that SCE-MAE is highly effective and robust outperforming existing SOTA methods by large margins of 20%-44% on the landmark matching and 9%-15% on the landmark detection tasks.

Recent trends in Large Vision Language Models (LVLMs) research have been increasingly focusing on advancing beyond general image understanding towards more nuanced object-level referential comprehension. In this paper we present and delve into the self-consistency capability of LVLMs a crucial aspect that reflects the models' ability to both generate informative captions for specific objects and subsequently utilize these captions to accurately re-identify the objects in a closed-loop process. This capability significantly mirrors the precision and reliability of fine-grained visual-language understanding. Our findings reveal that the self-consistency level of existing LVLMs falls short of expectations posing limitations on their practical applicability and potential. To address this gap we introduce a novel fine-tuning paradigm named Self-Consistency Tuning (SC-Tune). It features the synergistic learning of a cyclic describer-locator system. This paradigm is not only data-efficient but also exhibits generalizability across multiple LVLMs. Through extensive experiments we demonstrate that SC-Tune significantly elevates performance across a spectrum of object-level vision-language benchmarks and maintains competitive or improved performance on image-level vision-language benchmarks. Both our model and code will be publicly available at https://github.com/ivattyue/SC-Tune.

Novel view synthesis for dynamic scenes is still a challenging problem in computer vision and graphics. Recently Gaussian splatting has emerged as a robust technique to represent static scenes and enable high-quality and real-time novel view synthesis. Building upon this technique we propose a new representation that explicitly decomposes the motion and appearance of dynamic scenes into sparse control points and dense Gaussians respectively. Our key idea is to use sparse control points significantly fewer in number than the Gaussians to learn compact 6 DoF transformation bases which can be locally interpolated through learned interpolation weights to yield the motion field of 3D Gaussians. We employ a deformation MLP to predict time-varying 6 DoF transformations for each control point which reduces learning complexities enhances learning abilities and facilitates obtaining temporal and spatial coherent motion patterns. Then we jointly learn the 3D Gaussians the canonical space locations of control points and the deformation MLP to reconstruct the appearance geometry and dynamics of 3D scenes. During learning the location and number of control points are adaptively adjusted to accommodate varying motion complexities in different regions and an ARAP loss following the principle of as rigid as possible is developed to enforce spatial continuity and local rigidity of learned motions. Finally thanks to the explicit sparse motion representation and its decomposition from appearance our method can enable user-controlled motion editing while retaining high-fidelity appearances. Extensive experiments demonstrate that our approach outperforms existing approaches on novel view synthesis with a high rendering speed and enables novel appearance-preserved motion editing applications.

We introduce SAOR a novel approach for estimating the 3D shape texture and viewpoint of an articulated object from a single image captured in the wild. Unlike prior approaches that rely on pre-defined category-specific 3D templates or tailored 3D skeletons SAOR learns to articulate shapes from single-view image collections with a skeleton-free part-based model without requiring any 3D object shape priors. To prevent ill-posed solutions we propose a cross-instance consistency loss that exploits disentangled object shape deformation and articulation. This is helped by a new silhouette-based sampling mechanism to enhance viewpoint diversity during training. Our method only requires estimated object silhouettes and relative depth maps from off-the-shelf pre-trained networks during training. At inference time given a single-view image it efficiently outputs an explicit mesh representation. We obtain improved qualitative and quantitative results on challenging quadruped animals compared to relevant existing work.

Recently the Segment Anything Model (SAM) has showcased remarkable capabilities of zero-shot segmentation while NeRF (Neural Radiance Fields) has gained popularity as a method for various 3D problems beyond novel view synthesis. Though there exist initial attempts to incorporate these two methods into 3D segmentation they face the challenge of accurately and consistently segmenting objects in complex scenarios. In this paper we introduce the Segment Anything for NeRF in High Quality (SANeRF-HQ) to achieve high-quality 3D segmentation of any target object in a given scene. SANeRF-HQ utilizes SAM for open-world object segmentation guided by user-supplied prompts while leveraging NeRF to aggregate information from different viewpoints. To overcome the aforementioned challenges we employ density field and RGB similarity to enhance the accuracy of segmentation boundary during the aggregation. Emphasizing on segmentation accuracy we evaluate our method on multiple NeRF datasets where high-quality ground-truths are available or manually annotated. SANeRF-HQ shows a significant quality improvement over state-of-the-art methods in NeRF object segmentation provides higher flexibility for object localization and enables more consistent object segmentation across multiple views.

Zero-shot 6D object pose estimation involves the detection of novel objects with their 6D poses in cluttered scenes presenting significant challenges for model generalizability. Fortunately the recent Segment Anything Model (SAM) has showcased remarkable zero-shot transfer performance which provides a promising solution to tackle this task. Motivated by this we introduce SAM-6D a novel framework designed to realize the task through two steps including instance segmentation and pose estimation. Given the target objects SAM-6D employs two dedicated sub-networks namely Instance Segmentation Model (ISM) and Pose Estimation Model (PEM) to perform these steps on cluttered RGB-D images. ISM takes SAM as an advanced starting point to generate all possible object proposals and selectively preserves valid ones through meticulously crafted object matching scores in terms of semantics appearance and geometry. By treating pose estimation as a partial-to-partial point matching problem PEM performs a two-stage point matching process featuring a novel design of background tokens to construct dense 3D-3D correspondence ultimately yielding the pose estimates. Without bells and whistles SAM-6D outperforms the existing methods on the seven core datasets of the BOP Benchmark for both instance segmentation and pose estimation of novel objects.

Advancements in 3D instance segmentation have traditionally been tethered to the availability of annotated datasets limiting their application to a narrow spectrum of object categories. Recent efforts have sought to harness vision-language models like CLIP for open-set semantic reasoning yet these methods struggle to distinguish between objects of the same categories and rely on specific prompts that are not universally applicable. In this paper we introduce SAI3D a novel zero-shot 3D instance segmentation approach that synergistically leverages geometric priors and semantic cues derived from Segment Anything Model (SAM). Our method partitions a 3D scene into geometric primitives which are then progressively merged into 3D instance segmentations that are consistent with the multi-view SAM masks. Moreover we design a hierarchical region-growing algorithm with a dynamic thresholding mechanism which largely improves the robustness of fine-grained 3D scene parsing. Empirical evaluations on ScanNet Matterport3D and the more challenging ScanNet++ datasets demonstrate the superiority of our approach. Notably SAI3D outperforms existing open-vocabulary baselines and even surpasses fully-supervised methods in class-agnostic segmentation on ScanNet++. Our project page is at https://yd-yin.github.io/SAI3D/.

LiDAR-based 3D object detection plays an essential role in autonomous driving. Existing high-performing 3D object detectors usually build dense feature maps in the backbone network and prediction head. However the computational costs introduced by the dense feature maps grow quadratically as the perception range increases making these models hard to scale up to long-range detection. Some recent works have attempted to construct fully sparse detectors to solve this issue; nevertheless the resulting models either rely on a complex multi-stage pipeline or exhibit inferior performance. In this work we propose a fully sparse adaptive feature diffusion network (SAFDNet) for LiDAR-based 3D object detection. In SAFDNet an adaptive feature diffusion strategy is designed to address the center feature missing problem. We conducted extensive experiments on Waymo Open nuScenes and Argoverse2 datasets. SAFDNet performed slightly better than the previous SOTA on the first two datasets but much better on the last dataset which features long-range detection verifying the efficacy of SAFDNet in scenarios where long-range detection is required. Notably on Argoverse2 SAFDNet surpassed the previous best hybrid detector HEDNet by 2.6% mAP while being 2.1x faster and yielded 2.1% mAP gains over the previous best sparse detector FSDv2 while being 1.3x faster. The code will be available at https://github.com/zhanggang001/HEDNet.