CVPR 2024 Papers

We present Multi-Baseline Radiance Fields (MuRF) a general feed-forward approach to solving sparse view synthesis under multiple different baseline settings (small and large baselines and different number of input views). To render a target novel view we discretize the 3D space into planes parallel to the target image plane and accordingly construct a target view frustum volume. Such a target volume representation is spatially aligned with the target view which effectively aggregates relevant information from the input views for high-quality rendering. It also facilitates subsequent radiance field regression with a convolutional network thanks to its axis-aligned nature. The 3D context modeled by the convolutional network enables our method to synthesis sharper scene structures than prior works. Our MuRF achieves state-of-the-art performance across multiple different baseline settings and diverse scenarios ranging from simple objects (DTU) to complex indoor and outdoor scenes (RealEstate10K and LLFF). We also show promising zero-shot generalization abilities on the Mip-NeRF 360 dataset demonstrating the general applicability of MuRF.

Edge segmentation is well-known to be subjective due to personalized annotation styles and preferred granularity. However most existing deterministic edge detection methods produce only a single edge map for one input image. We argue that generating multiple edge maps is more reasonable than generating a single one considering the subjectivity and ambiguity of the edges. Thus motivated in this paper we propose multiple granularity edge detection called MuGE which can produce a wide range of edge maps from approximate object contours to fine texture edges. Specifically we first propose to design an edge granularity network to estimate the edge granularity from an individual edge annotation. Subsequently to guide the generation of diversified edge maps we integrate such edge granularity into the multi-scale feature maps in the spatial domain. Meanwhile we decompose the feature maps into low-frequency and high-frequency parts where the encoded edge granularity is further fused into the high-frequency part to achieve more precise control over the details of the produced edge maps. Compared to previous methods MuGE is able to not only generate multiple edge maps at different controllable granularities but also achieve a competitive performance on the BSDS500 and Multicue benchmark datasets.

Recently integrating video foundation models and large language models to build a video understanding system can overcome the limitations of specific pre-defined vision tasks. Yet existing systems can only handle videos with very few frames. For long videos the computation complexity memory cost and long-term temporal connection impose additional challenges. Taking advantage of the Atkinson-Shiffrin memory model with tokens in Transformers being employed as the carriers of memory in combination with our specially designed memory mechanism we propose the MovieChat to overcome these challenges. MovieChat achieves state-of-the-art performance in long video understanding along with the released MovieChat-1K benchmark with 1K long video and 14K manual annotations for validation of the effectiveness of our method. The code models and data can be found in https://rese1f.github.io/MovieChat.

Diffusion models generate images with an unprecedented level of quality but how can we freely rearrange image layouts? Recent works generate controllable scenes via learning spatially disentangled latent codes but these methods do not apply to diffusion models due to their fixed forward process. In this work we propose SceneDiffusion to optimize a layered scene representation during the diffusion sampling process. Our key insight is that spatial disentanglement can be obtained by jointly denoising scene renderings at different spatial layouts. Our generated scenes support a wide range of spatial editing operations including moving resizing cloning and layer-wise appearance editing operations including object restyling and replacing. Moreover a scene can be generated conditioned on a reference image thus enabling object moving for in-the-wild images. Notably this approach is training-free compatible with general text-to-image diffusion models and responsive in less than a second.

Existing diffusion-based video editing models have made gorgeous advances for editing attributes of a source video over time but struggle to manipulate the motion information while preserving the original protagonist's appearance and background. To address this we propose MotionEditor the first diffusion model for video motion editing. MotionEditor incorporates a novel content-aware motion adapter into ControlNet to capture temporal motion correspondence. While ControlNet enables direct generation based on skeleton poses it encounters challenges when modifying the source motion in the inverted noise due to contradictory signals between the noise (source) and the condition (reference). Our adapter complements ControlNet by involving source content to transfer adapted control signals seamlessly. Further we build up a two-branch architecture (a reconstruction branch and an editing branch) with a high-fidelity attention injection mechanism facilitating branch interaction. This mechanism enables the editing branch to query the key and value from the reconstruction branch in a decoupled manner making the editing branch retain the original background and protagonist appearance. We also propose a skeleton alignment algorithm to address the discrepancies in pose size and position. Experiments demonstrate the promising motion editing ability of MotionEditor both qualitatively and quantitatively. To the best of our knowledge MotionEditor is the first to use diffusion models specifically for video motion editing considering the origin dynamic background and camera movement.

We introduce Motion2VecSets a 4D diffusion model for dynamic surface reconstruction from point cloud sequences. While existing state-of-the-art methods have demonstrated success in reconstructing non-rigid objects using neural field representations conventional feed-forward networks encounter challenges with ambiguous observations from noisy partial or sparse point clouds. To address these challenges we introduce a diffusion model that explicitly learns the shape and motion distribution of non-rigid objects through an iterative denoising process of compressed latent representations. The diffusion-based priors enable more plausible and probabilistic reconstructions when handling ambiguous inputs. We parameterize 4D dynamics with latent sets instead of using global latent codes. This novel 4D representation allows us to learn local shape and deformation patterns leading to more accurate non-linear motion capture and significantly improving generalizability to unseen motions and identities. For more temporally-coherent object tracking we synchronously denoise deformation latent sets and exchange information across multiple frames. To avoid computational overhead we designed an interleaved space and time attention block to alternately aggregate deformation latents along spatial and temporal domains. Extensive comparisons against state-of-the-art methods demonstrate the superiority of our Motion2VecSets in 4D reconstruction from various imperfect observations.

Eliminating image blur produced by various kinds of motion has been a challenging problem. Dominant approaches rely heavily on model capacity to remove blurring by reconstructing residual from blurry observation in feature space. These practices not only prevent the capture of spatially variable motion in the real world but also ignore the tailored handling of various motions in image space. In this paper we propose a novel real-world deblurring filtering model called the Motion-adaptive Separable Collaborative (MISC) Filter. In particular we use a motion estimation network to capture motion information from neighborhoods thereby adaptively estimating spatially-variant motion flow mask kernels weights and offsets to obtain the MISC Filter. The MISC Filter first aligns the motion-induced blurring patterns to the motion middle along the predicted flow direction and then collaboratively filters the aligned image through the predicted kernels weights and offsets to generate the output. This design can handle more generalized and complex motion in a spatially differentiated manner. Furthermore we analyze the relationships between the motion estimation network and the residual reconstruction network. Extensive experiments on four widely used benchmarks demonstrate that our method provides an effective solution for real-world motion blur removal and achieves state-of-the-art performance. Code is available at https://github.com/ChengxuLiu/MISCFilter.

We introduce Motion Diversification Networks a novel framework for learning to generate realistic and diverse 3D human motion. Despite recent advances in deep generative motion modeling existing models often fail to produce samples that capture the full range of plausible and natural 3D human motion within a given context. The lack of diversity becomes even more apparent in applications where subtle and multi-modal 3D human forecasting is crucial for safety such as robotics and autonomous driving. Towards more realistic and functional 3D motion models we highlight limitations in existing generative modeling techniques particularly in overly simplistic latent code sampling strategies. We then introduce a transformer-based diversification mechanism that learns to effectively guide sampling in the latent space. Our proposed attention-based module queries multiple stochastic samples to flexibly predict a diverse set of latent codes which can be subsequently decoded into motion samples. The proposed framework achieves state-of-the-art diversity and accuracy prediction performance across a range of benchmarks and settings particularly when used to forecast intricate in-the-wild 3D human motion within complex urban environments. Our models datasets and code are available at https://mdncvpr.github.io/.

Motion blur is a frequently observed image artifact especially under insufficient illumination where exposure time has to be prolonged so as to collect more photons for a bright enough image. Rather than simply removing such blurring effects recent researches have aimed at decomposing a blurry image into multiple sharp images with spatial and temporal coherence. Since motion blur decomposition itself is highly ambiguous priors from neighbouring frames or human annotation are usually needed for motion disambiguation. In this paper inspired by the complementary exposure characteristics of a global shutter (GS) camera and a rolling shutter (RS) camera we propose to utilize the ordered scanline-wise delay in a rolling shutter image to robustify motion decomposition of a single blurry image. To evaluate this novel dual imaging setting we construct a triaxial system to collect realistic data as well as a deep network architecture that explicitly addresses temporal and contextual information through reciprocal branches for cross-shutter motion blur decomposition. Experiment results have verified the effectiveness of our proposed algorithm as well as the validity of our dual imaging setting.

Current diffusion or flow-based generative models for 3D shapes divide to two: distilling pre-trained 2D image diffusion models and training directly on 3D shapes. When training a diffusion or flow models on 3D shapes a crucial design choice is the shape representation. An effective shape representation needs to adhere three design principles: it should allow an efficient conversion of large 3D datasets to the representation form; it should provide a good tradeoff of approximation power versus number of parameters; and it should have a simple tensorial form that is compatible with existing powerful neural architectures. While standard 3D shape representations such as volumetric grids and point clouds do not adhere to all these principles simultaneously we advocate in this paper a new representation that does. We introduce Mosaic-SDF (M-SDF): a simple 3D shape representation that approximates the Signed Distance Function (SDF) of a given shape by using a set of local grids spread near the shape's boundary. The M-SDF representation is fast to compute for each shape individually making it readily parallelizable; it is parameter efficient as it only covers the space around the shape's boundary; and it has a simple matrix form compatible with Transformer-based architectures. We demonstrate the efficacy of the M-SDF representation by using it to train a 3D generative flow model including class-conditioned generation with the ShapeNetCore-V2 (3D Warehouse) dataset and text-to-3D generation using a dataset of about 600k caption-shape pairs.

Representation learning of pathology whole-slide images (WSIs) has been has primarily relied on weak supervision with Multiple Instance Learning (MIL). However the slide representations resulting from this approach are highly tailored to specific clinical tasks which limits their expressivity and generalization particularly in scenarios with limited data. Instead we hypothesize that morphological redundancy in tissue can be leveraged to build a task-agnostic slide representation in an unsupervised fashion. To this end we introduce PANTHER a prototype-based approach rooted in the Gaussian mixture model that summarizes the set of WSI patches into a much smaller set of morphological prototypes. Specifically each patch is assumed to have been generated from a mixture distribution where each mixture component represents a morphological exemplar. Utilizing the estimated mixture parameters we then construct a compact slide representation that can be readily used for a wide range of downstream tasks. By performing an extensive evaluation of PANTHER on subtyping and survival tasks using 13 datasets we show that 1) PANTHER outperforms or is on par with supervised MIL baselines and 2) the analysis of morphological prototypes brings new qualitative and quantitative insights into model interpretability. The code is available at https://github.com/mahmoodlab/Panther.

Neural rendering has demonstrated remarkable success in dynamic scene reconstruction. Thanks to the expressiveness of neural representations prior works can accurately capture the motion and achieve high-fidelity reconstruction of the target object. Despite this real-world video scenarios often feature large unobserved regions where neural representations struggle to achieve realistic completion. To tackle this challenge we introduce MorpheuS a framework for dynamic 360deg surface reconstruction from a casually captured RGB-D video. Our approach models the target scene as a canonical field that encodes its geometry and appearance in conjunction with a deformation field that warps points from the current frame to the canonical space. We leverage a view-dependent diffusion prior and distill knowledge from it to achieve realistic completion of unobserved regions. Experimental results on various real-world and synthetic datasets show that our method can achieve high-fidelity 360deg surface reconstruction of a deformable object from a monocular RGB-D video.

Recent advances in generative diffusion models have enabled the previously unfeasible capability of generating 3D assets from a single input image or a text prompt. In this work we aim to enhance the quality and functionality of these models for the task of creating controllable photorealistic human avatars. We achieve this by integrating a 3D morphable model into the state-of-the-art multi-view-consistent diffusion approach. We demonstrate that accurate conditioning of a generative pipeline on the articulated 3D model enhances the baseline model performance on the task of novel view synthesis from a single image. More importantly this integration facilitates a seamless and accurate incorporation of facial expression and body pose control into the generation process. To the best of our knowledge our proposed framework is the first diffusion model to enable the creation of fully 3D-consistent animatable and photorealistic human avatars from a single image of an unseen subject; extensive quantitative and qualitative evaluations demonstrate the advantages of our approach over existing state-of-the-art avatar creation models on both novel view and novel expression synthesis tasks. The code for our project is publicly available.

Recent 3D face reconstruction methods have made remarkable advancements yet there remain huge challenges in monocular high-quality facial reflectance reconstruction. Existing methods rely on a large amount of light-stage captured data to learn facial reflectance models. However the lack of subject diversity poses challenges in achieving good generalization and widespread applicability. In this paper we learn the reflectance prior in image space rather than UV space and present a framework named ID2Reflectance. Our framework can directly estimate the reflectance maps of a single image while using limited reflectance data for training. Our key insight is that reflectance data shares facial structures with RGB faces which enables obtaining expressive facial prior from inexpensive RGB data thus reducing the dependency on reflectance data. We first learn a high-quality prior for facial reflectance. Specifically we pretrain multi-domain facial feature codebooks and design a codebook fusion method to align the reflectance and RGB domains. Then we propose an identity-conditioned swapping module that injects facial identity from the target image into the pre-trained auto-encoder to modify the identity of the source reflectance image. Finally we stitch multi-view swapped reflectance images to obtain renderable assets. Extensive experiments demonstrate that our method exhibits excellent generalization capability and achieves state-of-the-art facial reflectance reconstruction results for in-the-wild faces.

Undoubtedly high-fidelity 3D hair is crucial for achieving realism artistic expression and immersion in computer graphics. While existing 3D hair modeling methods have achieved impressive performance the challenge of achieving high-quality hair reconstruction persists: they either require strict capture conditions making practical applications difficult or heavily rely on learned prior data obscuring fine-grained details in images. To address these challenges we propose MonoHair a generic framework to achieve high-fidelity hair reconstruction from a monocular video without specific requirements for environments. Our approach bifurcates the hair modeling process into two main stages: precise exterior reconstruction and interior structure inference. The exterior is meticulously crafted using our Patch-based Multi-View Optimization PMVO. This method strategically collects and integrates hair information from multiple views independent of prior data to produce a high-fidelity exterior 3D line map. This map not only captures intricate details but also facilitates the inference of the hair's inner structure. For the interior we employ a data-driven multi-view 3D hair reconstruction method. This method utilizes 2D structural renderings derived from the reconstructed exterior mirroring the synthetic 2D inputs used during training. This alignment effectively bridges the domain gap between our training data and real-world data thereby enhancing the accuracy and reliability of our interior structure inference. Lastly we generate a strand model and resolve the directional ambiguity by our hair growth algorithm. Our experiments demonstrate that our method exhibits robustness across diverse hairstyles and achieves state-of-the-art performance. For more results please refer to our project page https://keyuwu-cs.github.io/MonoHair/

3D object detection and pose estimation from a single-view image is challenging due to the high uncertainty caused by the absence of 3D perception. As a solution recent monocular 3D detection methods leverage additional modalities such as stereo image pairs and LiDAR point clouds to enhance image features at the expense of additional annotation costs. We propose using diffusion models to learn effective representations for monocular 3D detection without additional modalities or training data. We present MonoDiff a novel framework that employs the reverse diffusion process to estimate 3D bounding box and orientation. But considering the variability in bounding box sizes along different dimensions it is ineffective to sample noise from a standard Gaussian distribution. Hence we adopt a Gaussian mixture model to sample noise during the forward diffusion process and initialize the reverse diffusion process. Furthermore since the diffusion model generates the 3D parameters for a given object image we leverage 2D detection information to provide additional supervision by maintaining the correspondence between 3D/2D projection. Finally depending on the signal-to-noise ratio we incorporate a dynamic weighting scheme to account for the level of uncertainty in the supervision by projection at different timesteps. MonoDiff outperforms current state-of-the-art monocular 3D detection methods on the KITTI and Waymo benchmarks without additional depth priors. MonoDiff project is available at: https://dylran.github.io/monodiff.github.io.

Monocular 3D object detection has attracted widespread attention due to its potential to accurately obtain object 3D localization from a single image at a low cost. Depth estimation is an essential but challenging subtask of monocular 3D object detection due to the ill-posedness of 2D to 3D mapping. Many methods explore multiple local depth clues such as object heights and keypoints and then formulate the object depth estimation as an ensemble of multiple depth predictions to mitigate the insufficiency of single-depth information. However the errors of existing multiple depths tend to have the same sign which hinders them from neutralizing each other and limits the overall accuracy of combined depth. To alleviate this problem we propose to increase the complementarity of depths with two novel designs. First we add a new depth prediction branch named complementary depth that utilizes global and efficient depth clues from the entire image rather than the local clues to reduce the correlation of depth predictions. Second we propose to fully exploit the geometric relations between multiple depth clues to achieve complementarity in form. Benefiting from these designs our method achieves higher complementarity. Experiments on the KITTI benchmark demonstrate that our method achieves state-of-the-art performance without introducing extra data. In addition complementary depth can also be a lightweight and plug-and-play module to boost multiple existing monocular 3d object detectors. Code is available at https://github.com/elvintanhust/MonoCD.

The premise for the great advancement of molecular machine learning is dependent on a considerable amount of labeled data. In many real-world scenarios the labeled molecules are limited in quantity or laborious to derive. Recent pseudo-labeling methods are usually designed based on a single domain knowledge thereby failing to understand the comprehensive molecular configurations and limiting their adaptability to generalize across diverse biochemical context. To this end we introduce an innovative paradigm for dealing with the molecule pseudo-labeling named as Molecular Data Programming (MDP). In particular we adopt systematic supervision sources via crafting multiple graph labeling functions which covers various molecular structural knowledge of graph kernels molecular fingerprints and topological features. Each of them creates an uncertain and biased labels for the unlabeled molecules. To address the decision conflicts among the diverse pseudo-labels we design a label synchronizer to differentiably model confidences and correlations between the labeling functions which yields probabilistic molecular labels to adapt for specific applications. These probabilistic molecular labels are used to train a molecular classifier for improving its generalization capability. On eight benchmark datasets we empirically demonstrate the effectiveness of MDP on the weakly supervised molecule classification tasks.

Blind video quality assessment (BVQA) plays a pivotal role in evaluating and improving the viewing experience of end-users across a wide range of video-based platforms and services. Contemporary deep learning-based models primarily analyze video content in its aggressively subsampled format while being blind to the impact of the actual spatial resolution and frame rate on video quality. In this paper we propose a modular BVQA model and a method of training it to improve its modularity. Our model comprises a base quality predictor a spatial rectifier and a temporal rectifier responding to the visual content and distortion spatial resolution and frame rate changes on video quality respectively. During training spatial and temporal rectifiers are dropped out with some probabilities to render the base quality predictor a standalone BVQA model which should work better with the rectifiers. Extensive experiments on both professionally-generated content and user-generated content video databases show that our quality model achieves superior or comparable performance to current methods. Additionally the modularity of our model offers an opportunity to analyze existing video quality databases in terms of their spatial and temporal complexity.