3DV 2025 Papers

Mesh extraction from occupancy functions is a useful tool in creating synthetic datasets for computer vision. However, existing mesh extraction methods have artifacts or performance profiles that limit their use. We propose OcMesher, a mesh extractor that efficiently handles high-detail unbounded scenes with perfect view consistency, with easy export to downstream real-time engines. The main novelty of our solution is an algorithm to construct an octree based on a given occupancy function and multiple camera views. We performed extensive experiments, and demonstrate OcMesher's usefulness for synthetic training & benchmark datasets, generating real-time environments for embodied AI and mesh extraction from depthmaps or novel view synthesis methods.

Modern visual effects (VFX) software has made it possible for skilled artists to create imagery of virtually anything. However, the creation process remains laborious, complex, and largely inaccessible to everyday users. In this work, we present AutoVFX, a framework that automatically creates realistic and dynamic VFX videos from a single video and natural language instructions. By carefully integrating neural scene modeling, LLM-based code generation, and physical simulation, AutoVFX is able to provide physically-grounded, photorealistic editing effects that can be controlled directly using natural language instructions. We conduct extensive experiments to validate AutoVFX's efficacy across a diverse spectrum of videos and instructions. Quantitative and qualitative results suggest that AutoVFX outperforms all competing methods by a large margin in generative quality, instruction alignment, editing versatility, and physical plausibility.

This paper addresses the problem of reconstructing a scene online at the level of objects given an RGB-D video sequence. While current object-aware neural implicit representations hold promise, they are limited in online reconstruction efficiency and shape completion. Our main contributions to alleviate the above limitations are twofold. First, we propose a feature grid interpolation mechanism to continuously update grid-based object-centric neural implicit representations as new object parts are revealed. Second, we construct an object library with previously mapped objects in advance and leverage the corresponding shape priors to initialize geometric object models in new videos, subsequently completing them with novel views as well as synthesized past views to avoid losing original object details. Extensive experiments on synthetic environments from the Replica dataset, real-world ScanNet sequences and videos captured in our laboratory demonstrate that our approach outperforms state-of-the-art neural implicit models for this task in terms of reconstruction accuracy and completeness.

Synthesizing 3D whole bodies that realistically grasp objects is useful for animation, mixed reality, and robotics. This is challenging, because the hands and body need to look natural w.r.t. each other, the grasped object, as well as the local scene (i.e., a receptacle supporting the object). Moreover, training data for this task is really scarce, while capturing new data is expensive. Recent work goes beyond finite datasets via a divide-and-conquer approach; it first generates a “guiding” right-hand grasp, and then searches for bodies that match this. However, the guiding-hand synthesis lacks controllability and receptacle awareness, so it likely has an implausible direction (i.e., a body can’t match this without penetrating the receptacle) and needs corrections through major post-processing. Moreover, the body search needs exhaustive sampling and is expensive. These are strong limitations. We tackle these with a novel method called CWGrasp. Our key idea is that performing geometry-based reasoning “early on,” instead of “too late,” provides rich “control” signals for inference. To this end, CWGrasp first samples a plausible reaching-direction vector (used later for both the arm and hand) from a probabilistic model built via ray-casting from the object and collision checking. Then, it generates a reaching body with a desired arm direction, as well as a “guiding” grasping hand with a desired palm direction that complies with the arm’s one. Eventually, CWGrasp refines the body to match the “guiding” hand, while plausibly contacting the scene. Notably, generating already-compatible “parts” greatly simplifies the “whole”. Moreover, CWGrasp uniquely tackles both right and left-hand grasps. We evaluate on the GRAB and ReplicaGrasp datasets. CWGrasp outperforms baselines, at lower runtime and budget, while all components help performance. Code and models are available at https://gpaschalidis.github.io/cwgrasp.

We introduce GaussianAvatar-Editor, an innovative framework for text-driven editing of animatable Gaussian head avatars that can be fully controlled in expression, pose, and viewpoint. Unlike static 3D Gaussian editing, editing animatable 4D Gaussian avatars presents challenges related to motion occlusion and spatial-temporal inconsistency. To address these issues, we propose the Weighted Alpha Blending Equation (WABE). This function enhances the blending weight of visible Gaussians while suppressing the influence on non-visible Gaussians, effectively handling motion occlusion during editing. Furthermore, to improve editing quality and ensure 4D consistency, we incorporate conditional adversarial learning into the editing process. This strategy helps to refine the edited results and maintain consistency throughout the animation. By integrating these methods, our GaussianAvatar-Editor achieves photorealistic and consistent results in animatable 4D Gaussian editing. We conduct comprehensive experiments across various subjects to validate the effectiveness of our proposed techniques, which demonstrates the superiority of our approach over existing methods. More results and code are available at: \url{https://xiangyueliu.github.io/GaussianAvatar-Editor/}.

Text-driven 3D indoor scene generation is useful for gaming, film industry, and AR/VR applications. However, existing methods cannot faithfully capture the scene layout based on text descriptions, nor do they allow flexible editing of individual objects in the room. To address these problems, we present Ctrl-Room, which can generate convincing 3D rooms with designer-style layouts and high-fidelity textures from just a text prompt. Our key insight is to separate the modeling of layouts and appearance. Our proposed method consists of two stages: a Layout Generation Stage and an Appearance Generation Stage. The Layout Generation Stage trains a text-conditional diffusion model to learn the layout distribution with our holistic scene code parameterization. Next, the Appearance Generation Stage employs a fine-tuned ControlNet to produce a vivid panoramic image of the room guided by the 3D scene layout, then further upgrades to a panoramic NeRF model. Benefiting from the scene code parameterization, we can easily edit the generated room model through our mask-guided editing module, without expensive edit-specific training. Extensive experiments on the Structured3D dataset demonstrate that our method outperforms existing methods in producing more reasonable, view-consistent, and editable 3D rooms from text prompts.

Due to their performance and simplicity, rigid body simulators are often used in applications where the objects of interest can considered very stiff. However, no material has infinite stiffness, which means there are potentially cases where the non-zero compliance of the seemingly rigid object can cause a significant difference between its trajectories when simulated in a rigid body or deformable simulator. Similarly to how adversarial attacks are developed against image classifiers, we propose an adversarial attack against rigid body simulators. In this adversarial attack, we solve an optimization problem to construct perceptually rigid adversarial objects that have the same collision geometry and moments of mass to a reference object, so that they behave identically in rigid body simulations but maximally different in more accurate deformable simulations. We demonstrate the validity of our method by comparing simulations of several examples in commercially available simulators.

Dynamic neural radiance fields (dynamic NeRFs) have achieved remarkable successes in synthesizing novel views for 3D dynamic scenes. Traditional approaches typically necessitate full video sequences for the training phase prior to the synthesis of new views, akin to replaying a recording of a dynamic 3D event. In contrast, on-the-fly training allows for the immediate processing and rendering of dynamic scenes without the need for pre-training on full sequences, offering a more flexible and time-efficient solution for dynamic scene rendering tasks.In this paper, we propose a highly efficient on-the-fly training algorithm for dynamic NeRFs, named OD-NeRF. To accelerate the training process, our method minimizes the training required for the model at each frame by using: 1) a NeRF model conditioned on multi-view projected colors, which exhibits superior generalization across multiple frames with minimal training ,and 2) a transition and update algorithm that leverages the occupancy grid from the last frame to sample efficiently at the current frame. Our algorithm can achieve an interactive training speed of 10FPS on synthetic dynamic scenes on-the-fly, and a 3$\times$-9$\times$ training speed-up compared to the state-of-the-art on-the-fly NeRF on real-world dynamic scenes.

Tracking human object interaction from videos is important to understand human behavior from the rapidly growing stream of video data. Previous video-based methods require predefined object templates while single-image-based methods are template-free but lack temporal consistency. In this paper, we present a method to track human object interaction without any object shape templates. We decompose the 4D tracking problem into per-frame pose tracking and canonical shape optimization. We first apply a single-view reconstruction method to obtain temporally-inconsistent per-frame interaction reconstructions. Then, for the human, we propose an efficient autoencoder to predict SMPL vertices directly from the per-frame reconstructions, introducing temporally consistent correspondence. For the object, we introduce a pose estimator that leverages temporal information to predict smooth object rotations under occlusions. To train our model, we propose a method to generate synthetic interaction videos and synthesize in total 10 hour videos of 8.3k sequences with full 3D ground truth. Experiments on BEHAVE and InterCap show that our method significantly outperforms previous template-based video tracking and single-frame reconstruction methods. Our proposed synthetic video dataset also allows training video-based methods that generalize to real-world videos. Our code and dataset are publicly released.

State-of-the-art novel view synthesis methods achieve impressive results for multi-view captures of static 3D scenes. However, the reconstructed scenes still lack “liveliness,” a key component for creating engaging 3D experiences. Recently, novel video diffusion models generate realistic videos with complex motion and enable animations of 2D images, however they cannot naively be used to animate 3D scenes as they lack multi-view consistency. To breathe life into the static world, we propose Gaussians2Life, a method for animating parts of high-quality 3D scenes in a Gaussian Splatting representation. Our key idea is to leverage powerful video diffusion models as the generative component of our model and to combine these with a robust technique to lift 2D videos into meaningful 3D motion. We find that, in contrast to prior work, this enables realistic animations of complex, pre-existing 3D scenes in a robust manner and further enables the animation of a large variety of object classes, while related work is mostly focused on prior-based character animation, or single 3D objects due to biases of video diffusion models. Our model can readily be used to create immersive and engaging 3D experiences for arbitrary scenes in a consistent manner.

This work leverages shadow cues in a scene to infer the surrounding illumination of the shadow-casting object. Unlike prior works that optimize a discrete environment map, we model scene illumination using a mixture of spherical Gaussians (SGs). SG illumination provides more intuitive relations to shadow appearance and offers a more compact parameterization compared to discrete environment maps. To estimate SG parameters, we employ an SG-based, differentiable, closed-form rendering equation to explain the shading of the shadow plane and minimize a photometric loss between the rendered and observed shadow plane shading. Experiments on synthetic and real-world images under various surrounding illumination demonstrate that our method estimates illumination more accurately than approaches based on discrete environment maps. With our estimated lighting, consistent shadow effects are realized when blending virtual objects into real-world images.

Over the past years, significant progress was made in creating photorealistic and drivable 3D avatars solely from videos of real humans. However, a core remaining challenge is the fine-grained and user-friendly editing of clothing styles by means of textual descriptions. In particular, text-based edits of full-body avatars should satisfy two properties: 1) Spatio-temporal consistency, i.e. the dynamics, and the photo-real quality of the original avatar, should remain intact; 2) The final result should respect the user-specified edit. To this end, we present TEDRA the first method allowing text-based edits of an avatar, that are photorealistic, space-time coherent, dynamic, and enable skeletal pose and view control. We leverage a pre-trained avatar that is represented as a signed distance and radiance field, which is anchored to an explicit and deformable mesh template. After a pre-training stage, we obtain a drivable and photo-real digital counterpart of the real actor. Specifically, we employ an optimization strategy to integrate various frames capturing distinct camera perspectives and the dynamics of a video performance into a unified diffusion model. Utilizing this personalized diffusion model, we modify the dynamic avatar based on a provided text prompt, introducing the Normal Aligned Identity Preserving Score Distillation Sampling (NAIP-SDS) within a model-based guidance framework. Additionally, we implement a time-step annealing strategy to ensure the high quality of our edits. Our results demonstrate a clear improvement over prior work in terms of functionality and visual quality. Thus, our method is a clear step towards intuitive and photorealistic editability of digital avatars, which explicitly accounts for dynamics and allows skeletal pose and view control at test time.

Depth completion using lightweight time-of-flight (ToF) depth sensors is attractive due to their low cost. However, lightweight ToF sensors usually have a limited field of view (FOV) compared with cameras. Thus, only pixels in the zone area of the image can be associated with depth signals. Previous methods fail to propagate depth features from the zone area to the outside-zone area effectively, thus suffering from degraded depth completion performance outside the zone. To this end, this paper proposes the CFPNet to achieve cross-zone feature propagation from the zone area to the outside-zone area with two novel modules. The first is a direct-attention-based propagation module (DAPM), which enforces direct cross-zone feature acquisition. The second is a large-kernel-based propagation module (LKPM), which realizes cross-zone feature propagation by utilizing convolution layers with kernel sizes up to 31. CFPNet achieves state-of-the-art (SOTA) depth completion performance by combining these two modules properly, as verified by extensive experimental results on the ZJU-L5 dataset. The code is available at https://github.com/denyingmxd/CFPNet.

We present BiGS, an image-based novel view synthesis technique designed to model and render 3D objects with surface and volumetric materials under dynamic illumination, achieving real-time relighting of 3D objects with the rasterization algorithm of Gaussian Splatting. Our method represents light- and view-dependent scattering via bidirectional spherical harmonics that does not use a specific surface normal-related reflectance function, making it more compatible with volumetric representations like Gaussian splatting, where the normals are undefined. We demonstrate our method by reconstructing and rendering objects with complex materials on synthetic and captured One-Light-At-a-Time (OLAT) datasets, showcasing various photorealistic appearances our method captures and the real-time performance.

We present UrbanIR (Urban Scene Inverse Rendering), a new inverse graphics model that enables realistic, free-viewpoint renderings of scenes under various lighting conditions with a single video. It accurately infers shape, albedo, visibility, and sun and sky illumination from wide-baseline videos, such as those from car-mounted cameras, differing from NeRF's dense view settings. In this context, standard methods often yield subpar geometry and material estimates, such as inaccurate roof representations and numerous `floaters.' UrbanIR addresses these issues with novel losses that reduce errors in inverse graphics inference and rendering artifacts. Its techniques allow for precise shadow volume estimation in the original scene. The model's outputs support controllable editing, enabling photorealistic free-viewpoint renderings of night simulations, relit scenes, and inserted objects, marking a significant improvement over existing state-of-the-art methods. Our code and data will be made publicly available upon acceptance.

This paper presents a novel approach for cross-view synthesis aimed at generating plausible ground-level images from corresponding satellite imagery or vice versa. We refer to these tasks as satellite-to-ground (Sat2Grd) and ground-to-satellite (Grd2Sat) synthesis, respectively. Unlike previous works that typically focus on one-to-one generation, producing a single output image from a single input image, our approach acknowledges the inherent one-to-many nature of the problem. This recognition stems from the challenges posed by differences in illumination, weather conditions, and occlusions between the two views. To effectively model this uncertainty, we leverage recent advancements in diffusion models. Specifically, we exploit random Gaussian noise to represent the diverse possibilities learnt from the target view data. Additionally, we introduce a Geometry-guided Cross-view Condition (GCC) strategy to establish explicit geometric correspondences between satellite and street-view features. This enables us to resolve the geometry ambiguity introduced by camera pose between image pairs, boosting the performance of cross-view image synthesis. Through extensive quantitative and qualitative analyses on three benchmark cross-view datasets, we demonstrate the superiority of our proposed geometry-guided cross-view condition over baseline methods, including recent state-of-the-art approaches in cross-view image synthesis. Our method generates images of higher quality, fidelity, and diversity than other state-of-the-art approaches.

Single-view 3D reconstruction is currently approached from two dominant perspectives: reconstruction of scenes with limited diversity using 3D data supervision or reconstruction of diverse singular objects using large image priors. However, real-world scenarios are far more complex and exceed the capabilities of these methods. We therefore propose a hybrid method following a divide-and-conquer strategy. We first process the scene holistically, extracting depth and semantic information, and then leverage an object-level method for the detailed reconstruction of individual components. By splitting the problem into simpler tasks, our system is able to generalize to various types of scenes without retraining or fine-tuning. We purposely design our pipeline to be highly modular with independent, self-contained modules, to avoid the need for end-to-end training of the whole system. This enables the pipeline to naturally improve as future methods can replace the individual modules. We demonstrate the reconstruction performance of our approach on both synthetic and real-world scenes, comparing favorable against prior works. Project page: https://andreeadogaru.github.io/Gen3DSR

Freehand 3D sketches are a great medium to ideate and create visual content. However, generating 3D models from such rough sketches remains an unsolved, non-trivial task. We present a complete end-to-end interactive framework for rapid, incremental modelling from sparse, irregular 3D sketches. At the core of our solution, is 'sketchTransformer', a two-staged transformer network architecture, that fits parametric surface patches to a set of sketch strokes. We devise a novel pseudo height field representation that enables sketchTransformer to handle the noise and sparseness in the input strokes. Our method interactively evolves the surface model while maintaining smooth joins to nearby patches. We show two frontends for our framework, one on the desktop and as a mobile AR application, to illustrate how our method complements a standard 3D modelling pipelines. We can robustly handle a large variety of input 3D strokes, that competing methods cannot parse adequately.

Surface reconstruction from multiple, calibrated images is a challenging task - often requiring a large number of collected images with significant overlap. We look at the specific case of human foot reconstruction. As with previous successful foot reconstruction work, we seek to extract rich per-pixel geometry cues from multi-view RGB images, and fuse these into a final 3D object. Our method, FOCUS, tackles this problem with 3 main contributions: (i) SynFoot2, an extension of an existing synthetic foot dataset to include a new data type: dense correspondence with the parameterized foot model FIND; (ii) an uncertainty-aware dense correspondence predictor trained on our synthetic dataset; (iii) two methods for reconstructing a 3D surface from dense correspondence predictions: one inspired by Structure-from-Motion, and one optimization-based using the FIND model. We show that our reconstruction achieves state-of-the-art reconstruction quality in a few-view setting, performing comparably to state-of-the-art when many views are available, and runs substantially faster. We release our synthetic dataset to the research community. Code is available at: https://github.com/OllieBoyne/FOCUS