EG 2025 - Full Papers - CGF 44-Issue 2

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Learning Image Fractals Using Chaotic Differentiable Point Splatting
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Djeacoumar, Adarsh; Mujkanovic, Felix; Seidel, Hans-Peter; Leimkühler, Thomas; Bousseau, Adrien; Day, Angela
Fractal geometry, defined by self-similar patterns across scales, is crucial for understanding natural structures. This work addresses the fractal inverse problem, which involves extracting fractal codes from images to explain these patterns and synthesize them at arbitrary finer scales. We introduce a novel algorithm that optimizes Iterated Function System parameters using a custom fractal generator combined with differentiable point splatting. By integrating both stochastic and gradient-based optimization techniques, our approach effectively navigates the complex energy landscapes typical of fractal inversion, ensuring robust performance and the ability to escape local minima. We demonstrate the method's effectiveness through comparisons with various fractal inversion techniques, highlighting its ability to recover high-quality fractal codes and perform extensive zoom-ins to reveal intricate patterns from just a single image.
Multi-Modal Instrument Performances (MMIP): A Musical Database
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Kyriakou, Theodoros; Aristidou, Andreas; Charalambous, Panayiotis; Bousseau, Adrien; Day, Angela
Musical instrument performances are multimodal creative art forms that integrate audiovisual elements, resulting from musicians' interactions with instruments through body movements, finger actions, and facial expressions. Digitizing such performances for archiving, streaming, analysis, or synthesis requires capturing every element that shapes the overall experience, which is crucial for preserving the performance's essence. In this work, following current trends in large-scale dataset development for deep learning analysis and generative models, we introduce the Multi-Modal Instrument Performances (MMIP) database (https://mmip.cs.ucy.ac.cy). This is the first dataset to incorporate synchronized high-quality 3D motion capture data for the body, fingers, facial expressions, and instruments, along with audio, multi-angle videos, and MIDI data. The database currently includes 3.5 hours of performances featuring three instruments: guitar, piano, and drums. Additionally, we discuss the challenges of acquiring these multi-modal data, detailing our approach to data collection, signal synchronization, annotation, and metadata management. Our data formats align with industry standards for ease of use, and we have developed an open-access online repository that offers a user-friendly environment for data exploration, supporting data organization, search capabilities, and custom visualization tools. Notable features include a MIDI-to-instrument animation project for visualizing the instruments and a script for playing back FBX files with synchronized audio in a web environment.
Learning Metric Fields for Fast Low-Distortion Mesh Parameterizations
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Fargion, Guy; Weber, Ofir; Bousseau, Adrien; Day, Angela
We present a fast and robust method for computing an injective parameterization with low isometric distortion for disk-like triangular meshes. Harmonic function-based methods, with their rich mathematical foundation, are widely used. Harmonic maps are particularly valuable for ensuring injectivity under certain boundary conditions. In addition, they offer computational efficiency by forming a linear subspace [FW22]. However, this restricted subspace often leads to significant isometric distortion, especially for highly curved surfaces. Conversely, methods that operate in the full space of piecewise linear maps [SPSH∗17] achieve lower isometric distortion, but at a higher computational cost. Aigerman et al. [AGK∗22] pioneered a parameterization method that uses deep neural networks to predict the Jacobians of the map at mesh triangles, and integrates them into an explicit map by solving a Poisson equation. However, this approach often results in significant Poisson reconstruction errors due to the inability to ensure the integrability of the predicted neural Jacobian field, leading to unbounded distortion and lack of local injectivity. We propose a hybrid method that combines the speed and robustness of harmonic maps with the generality of deep neural networks to produce injective maps with low isometric distortion much faster than state-of-the-art methods. The core concept is simple but powerful. Instead of learning Jacobian fields, we learn metric tensor fields over the input mesh, resulting in a customized Laplacian matrix that defines a harmonic map in a modified metric [WGS23]. Our approach ensures injectivity, offers great computational efficiency, and produces significantly lower isometric distortion compared to straightforward harmonic maps.
"Wild West" of Evaluating Speech-Driven 3D Facial Animation Synthesis: A Benchmark Study
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Haque, Kazi Injamamul; Pavlou, Alkiviadis; Yumak, Zerrin; Bousseau, Adrien; Day, Angela
Recent advancements in the field of audio-driven 3D facial animation have accelerated rapidly, with numerous papers being published in a short span of time. This surge in research has garnered significant attention from both academia and industry with its potential applications on digital humans. Various approaches, both deterministic and non-deterministic, have been explored based on foundational advancements in deep learning algorithms. However, there remains no consensus among researchers on standardized methods for evaluating these techniques. Additionally, rather than converging on a common set of datasets and objective metrics suited for specific methods, recent works exhibit considerable variation in experimental setups. This inconsistency complicates the research landscape, making it difficult to establish a streamlined evaluation process and rendering many cross-paper comparisons challenging. Moreover, the common practice of A/B testing in perceptual studies focus only on two common metrics and not sufficient for non-deterministic and emotion-enabled approaches. The lack of correlations between subjective and objective metrics points out that there is a need for critical analysis in this space. In this study, we address these issues by benchmarking state-of-the-art deterministic and non-deterministic models, utilizing a consistent experimental setup across a carefully curated set of objective metrics and datasets. We also conduct a perceptual user study to assess whether subjective perceptual metrics align with the objective metrics. Our findings indicate that model rankings do not necessarily generalize across datasets, and subjective metric ratings are not always consistent with their corresponding objective metrics. The supplementary video, edited code scripts for training on different datasets and documentation related to this benchmark study are made publicly available- https://galib360.github.io/face-benchmark-project/.
StyleBlend: Enhancing Style-Specific Content Creation in Text-to-Image Diffusion Models
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Chen, Zichong; Wang, Shijin; Zhou, Yang; Bousseau, Adrien; Day, Angela
Synthesizing visually impressive images that seamlessly align both text prompts and specific artistic styles remains a significant challenge in Text-to-Image (T2I) diffusion models. This paper introduces StyleBlend, a method designed to learn and apply style representations from a limited set of reference images, enabling content synthesis of both text-aligned and stylistically coherent. Our approach uniquely decomposes style into two components, composition and texture, each learned through different strategies. We then leverage two synthesis branches, each focusing on a corresponding style component, to facilitate effective style blending through shared features without affecting content generation. StyleBlend addresses the common issues of text misalignment and weak style representation that previous methods have struggled with. Extensive qualitative and quantitative comparisons demonstrate the superiority of our approach.
Neural Geometry Processing via Spherical Neural Surfaces
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Williamson, Romy; Mitra, Niloy J.; Bousseau, Adrien; Day, Angela
Neural surfaces (e.g., neural map encoding, deep implicit, and neural radiance fields) have recently gained popularity because of their generic structure (e.g., multi-layer perceptron) and easy integration with modern learning-based setups. Traditionally, we have a rich toolbox of geometry processing algorithms designed for polygonal meshes to analyze and operate on surface geometry. Without an analogous toolbox, neural representations are typically discretized and converted into a mesh, before applying any geometry processing algorithm. This is unsatisfactory and, as we demonstrate, unnecessary. In this work, we propose a spherical neural surface representation for genus-0 surfaces and demonstrate how to compute core geometric operators directly on this representation. Namely, we estimate surface normals and first and second fundamental forms of the surface, as well as compute surface gradient, surface divergence and Laplace Beltrami operator on scalar/vector fields defined on the surface. Our representation is fully seamless, overcoming a key limitation of similar explicit representations such as Neural Surface Maps [MAKM21]. These operators, in turn, enable geometry processing directly on the neural representations without any unnecessary meshing. We demonstrate illustrative applications in (neural) spectral analysis, heat flow and mean curvature flow, and evaluate robustness to isometric shape variations. We propose theoretical formulations and validate their numerical estimates, against analytical estimates, mesh-based baselines, and neural alternatives, where available. By systematically linking neural surface representations with classical geometry processing algorithms, we believe this work can become a key ingredient in enabling neural geometry processing. Code is available via the project webpage.
Lipschitz Pruning: Hierarchical Simplification of Primitive-Based SDFs
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Barbier, Wilhem; Sanchez, Mathieu; Paris, Axel; Michel, Élie; Lambert, Thibaud; Boubekeur, Tamy; Paulin, Mathias; Thonat, Theo; Bousseau, Adrien; Day, Angela
Rendering tree-based analytical Signed Distance Fields (SDFs) through sphere tracing often requires to evaluate many primitives per tracing step, for many steps per pixel of the end image. This cost quickly becomes prohibitive as the number of primitives that constitute the SDF grows. In this paper, we alleviate this cost by computing local pruned trees that are equivalent to the full tree within their region of space while being much faster to evaluate. We introduce an efficient hierarchical tree pruning method based on the Lipschitz property of SDFs, which is compatible with hard and smooth CSG operators. We propose a GPU implementation that enables real-time sphere tracing of complex SDFs composed of thousands of primitives with dynamic animation. Our pruning technique provides significant speedups for SDF evaluation in general, which we demonstrate on sphere tracing tasks but could also lead to significant improvement for SDF discretization or polygonization.
Deformed Tiling and Blending: Application to the Correction of Distortions Implied by Texture Mapping
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Wendling, Quentin; Ravaglia, Joris; Sauvage, Basile; Bousseau, Adrien; Day, Angela
The prevailing model in virtual 3D scenes is a 3D surface, which a texture is mapped onto, through a parameterization from the texture plane. We focus on accounting for the parameterization during the texture creation process, to control the deformations and remove the cuts induced by the mapping. We rely on the tiling and blending, a real-time and parallel algorithm that generates an arbitrary large texture from a small input example. Our first contribution is to enhance the tiling and blending with a deformation field, which controls smooth spatial variations in the texture plane. Our second contribution is to derive, from a parameterized triangle mesh, a deformation field to compensate for texture distortions and to control for the texture orientation. Our third contribution is a technique to enforce texture continuity across the cuts, thanks to a proper tile selection. This opens the door to interactive sessions with artistic control, and real-time rendering with improved visual quality.
D-NPC: Dynamic Neural Point Clouds for Non-Rigid View Synthesis from Monocular Video
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Kappel, Moritz; Hahlbohm, Florian; Scholz, Timon; Castillo, Susana; Theobalt, Christian; Eisemann, Martin; Golyanik, Vladislav; Magnor, Marcus; Bousseau, Adrien; Day, Angela
Dynamic reconstruction and spatiotemporal novel-view synthesis of non-rigidly deforming scenes recently gained increased attention. While existing work achieves impressive quality and performance on multi-view or teleporting camera setups, most methods fail to efficiently and faithfully recover motion and appearance from casual monocular captures. This paper contributes to the field by introducing a new method for dynamic novel view synthesis from monocular video, such as casual smartphone captures. Our approach represents the scene as a dynamic neural point cloud, an implicit time-conditioned point distribution that encodes local geometry and appearance in separate hash-encoded neural feature grids for static and dynamic regions. By sampling a discrete point cloud from our model, we can efficiently render high-quality novel views using a fast differentiable rasterizer and neural rendering network. Similar to recent work, we leverage advances in neural scene analysis by incorporating data-driven priors like monocular depth estimation and object segmentation to resolve motion and depth ambiguities originating from the monocular captures. In addition to guiding the optimization process, we show that these priors can be exploited to explicitly initialize our scene representation to drastically improve optimization speed and final image quality. As evidenced by our experimental evaluation, our dynamic point cloud model not only enables fast optimization and real-time frame rates for interactive applications, but also achieves competitive image quality on monocular benchmark sequences. Our code and data are available online https://moritzkappel.github.io/projects/dnpc/.
Versatile Physics-based Character Control with Hybrid Latent Representation
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Bae, Jinseok; Won, Jungdam; Lim, Donggeun; Hwang, Inwoo; Kim, Young Min; Bousseau, Adrien; Day, Angela
We present a versatile latent representation that enables physically simulated character to efficiently utilize motion priors. To build a powerful motion embedding that is shared across multiple tasks, the physics controller should employ rich latent space that is easily explored and capable of generating high-quality motion. We propose integrating continuous and discrete latent representations to build a versatile motion prior that can be adapted to a wide range of challenging control tasks. Specifically, we build a discrete latent model to capture distinctive posterior distribution without collapse, and simultaneously augment the sampled vector with the continuous residuals to generate high-quality, smooth motion without jittering. We further incorporate Residual Vector Quantization, which not only maximizes the capacity of the discrete motion prior, but also efficiently abstracts the action space during the task learning phase. We demonstrate that our agent can produce diverse yet smooth motions simply by traversing the learned motion prior through unconditional motion generation. Furthermore, our model robustly satisfies sparse goal conditions with highly expressive natural motions, including head-mounted device tracking and motion in-betweening at irregular intervals, which could not be achieved with existing latent representations.
Does 3D Gaussian Splatting Need Accurate Volumetric Rendering?
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Celarek, Adam; Kopanas, Georgios; Drettakis, George; Wimmer, Michael; Kerbl, Bernhard; Bousseau, Adrien; Day, Angela
Since its introduction, 3D Gaussian Splatting (3DGS) has become an important reference method for learning 3D representations of a captured scene, allowing real-time novel-view synthesis with high visual quality and fast training times. Neural Radiance Fields (NeRFs), which preceded 3DGS, are based on a principled ray-marching approach for volumetric rendering. In contrast, while sharing a similar image formation model with NeRF, 3DGS uses a hybrid rendering solution that builds on the strengths of volume rendering and primitive rasterization. A crucial benefit of 3DGS is its performance, achieved through a set of approximations, in many cases with respect to volumetric rendering theory. A naturally arising question is whether replacing these approximations with more principled volumetric rendering solutions can improve the quality of 3DGS. In this paper, we present an in-depth analysis of the various approximations and assumptions used by the original 3DGS solution. We demonstrate that, while more accurate volumetric rendering can help for low numbers of primitives, the power of efficient optimization and the large number of Gaussians allows 3DGS to outperform volumetric rendering despite its approximations.
VRSurf: Surface Creation from Sparse, Unoriented 3D Strokes
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Sureshkumar, Anandhu; Parakkat, Amal Dev; Bonneau, Georges-Pierre; Hahmann, Stefanie; Cani, Marie-Paule; Bousseau, Adrien; Day, Angela
Although intuitive, sketching a closed 3D shape directly in an immersive environment results in an unordered set of arbitrary strokes, which can be difficult to assemble into a closed surface. We tackle this challenge by introducing VRSurf, a surfacing method inspired by a balloon inflation metaphor: Seeded in the sparse scaffold formed by the strokes, a smooth, closed surface is inflated to progressively interpolate the input strokes, sampled into lists of points. These are treated in a divide-and-conquer manner, which allows for automatically triggering some additional balloon inflation followed by fusion if the current inflation stops due to a detected concavity. While the input strokes are intended to belong to the same smooth 3D shape, our method is robust to coarse VR input and does not require strokes to be aligned. We simply avoid intersecting strokes that might give an inconsistent surface position due to the roughness of the VR drawing. Moreover, no additional topological information is required, and all the user needs to do is specify the initial seeding location for the first balloon. The results show that VRsurf can efficiently generate smooth surfaces that interpolate sparse sets of unoriented strokes. Validation includes a side-by-side comparison with other reconstruction methods on the same input VR sketch. We also check that our solution matches the user's intent by applying it to strokes that were sketched on an existing 3D shape and comparing what we get to the original one.
ReConForM: Real-time Contact-aware Motion Retargeting for more Diverse Character Morphologies
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Cheynel, Théo; Rossi, Thomas; Bellot-Gurlet, Baptiste; Rohmer, Damien; Cani, Marie-Paule; Bousseau, Adrien; Day, Angela
Preserving semantics, in particular in terms of contacts, is a key challenge when retargeting motion between characters of different morphologies. Our solution relies on a low-dimensional embedding of the character's mesh, based on rigged key vertices that are automatically transferred from the source to the target. Motion descriptors are extracted from the trajectories of these key vertices, providing an embedding that contains combined semantic information about both shape and pose. A novel, adaptive algorithm is then used to automatically select and weight the most relevant features over time, enabling us to efficiently optimize the target motion until it conforms to these constraints, so as to preserve the semantics of the source motion. Our solution allows extensions to several novel use-cases where morphology and mesh contacts were previously overlooked, such as multi-character retargeting and motion transfer on uneven terrains. As our results show, our method is able to achieve real-time retargeting onto a wide variety of characters. Extensive experiments and comparison with state-of-the-art methods using several relevant metrics demonstrate improved results, both in terms of motion smoothness and contact accuracy.
Neural Film Grain Rendering
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Lesné, Gwilherm; Gousseau, Yann; Ladjal, Saïd; Newson, Alasdair; Bousseau, Adrien; Day, Angela
Film grain refers to the specific texture of film-acquired images, due to the physical nature of photographic film. Being a visual signature of such images, there is a strong interest in the film-industry for the rendering of these textures for digital images. Some previous works are able to closely mimic the physics of films and produce high quality results, but are computationally expensive. We propose a method based on a lightweight neural network and a texture aware loss function, achieving realistic results with very low complexity, even for large grains and high resolutions. We evaluate our algorithm both quantitatively and qualitatively with respect to previous work.
Rest Shape Optimization for Sag-Free Discrete Elastic Rods
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Takahashi, Tetsuya; Batty, Christopher; Bousseau, Adrien; Day, Angela
We propose a new rest shape optimization framework to achieve sag-free simulations of discrete elastic rods. To optimize rest shape parameters, we formulate a minimization problem based on the kinetic energy with a regularizer while imposing box constraints on these parameters to ensure the system's stability. Our method solves the resulting constrained minimization problem via the Gauss-Newton algorithm augmented with penalty methods. We demonstrate that the optimized rest shape parameters enable discrete elastic rods to achieve static equilibrium for a wide range of strand geometries and material parameters.
Adaptive Multi-view Radiance Caching for Heterogeneous Participating Media
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Stadlbauer, Pascal; Tatzgern, Wolfgang; Mueller, Joerg H.; Winter, Martin; Stojanovic, Robert; Weinrauch, Alexander; Steinberger, Markus; Bousseau, Adrien; Day, Angela
Achieving lifelike atmospheric effects, such as fog, is essential in creating immersive environments and poses a formidable challenge in real-time rendering. Highly realistic rendering of complex lighting interacting with dynamic fog can be very resourceintensive, due to light bouncing through a complex participating media multiple times. We propose an approach that uses a multi-layered spherical harmonics probe grid to share computations temporarily. In addition, this world-space storage enables the sharing of radiance data between multiple viewers. In the context of cloud rendering this means faster rendering and a significant enhancement in overall rendering quality with efficient resource utilization.
Towards Scaling-Invariant Projections for Data Visualization
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Dierkes, Joel; Stelter, Daniel; Rössl, Christian; Theisel, Holger; Bousseau, Adrien; Day, Angela
Finding projections of multidimensional data domains to the 2D screen space is a well-known problem. Multidimensional data often comes with the property that the dimensions are measured in different physical units, which renders the ratio between dimensions, i.e., their scale, arbitrary. The result of common projections, like PCA, t-SNE, or MDS, depends on this ratio, i.e., these projections are variant to scaling. This results in an undesired subjective view of the data, and thus, their projection. Simple solutions like normalization of each dimension are widely used, but do not always give high-quality results. We propose to visually analyze the space of all scalings and to find optimal scalings w.r.t. the quality of the visualization. For this, we evaluate different quality criteria on scatter plots. Given a quality criterion, our approach finds scalings that yield good visualizations with little to no user input using numerical optimization. Simultaneously, our method results in a scaling invariant projection, proposing an objective view to the projected data. We show for several examples that such an optimal scaling can significantly improve the visualization quality.
S-ACORD: Spectral Analysis of COral Reef Deformation
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Alon-Borissiouk, Naama; Yuval, Matan; Treibitz, Tali; Ben-Chen, Mirela; Bousseau, Adrien; Day, Angela
We propose an efficient pipeline to register, detect, and analyze changes in 3D models of coral reefs captured over time. Corals have complex structures with intricate geometric features at multiple scales. 3D reconstructions of corals (e.g., using Photogrammetry) are represented by dense triangle meshes with millions of vertices. Hence, identifying correspondences quickly using conventional state-of-the-art algorithms is challenging. To address this gap we employ the Globally Optimal Iterative Closest Point (GO-ICP) algorithm to compute correspondences, and a fast approximation algorithm (FastSpectrum) to extract the eigenvectors of the Laplace-Beltrami operator for creating functional maps. Finally, by visualizing the distortion of these maps we identify changes in the coral reefs over time. Our approach is fully automatic, does not require user specified landmarks or an initial map, and surpasses competing shape correspondence methods on coral reef models. Furthermore, our analysis has detected the changes manually marked by humans, as well as additional changes at a smaller scale that were missed during manual inspection. We have additionally used our system to analyse a coral reef model that was too extensive for manual analysis, and validated that the changes identified by the system were correct.
SOBB: Skewed Oriented Bounding Boxes for Ray Tracing
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Kácerik, Martin; Bittner, Jirí; Bousseau, Adrien; Day, Angela
We propose skewed oriented bounding boxes (SOBB) as a novel bounding primitive for accelerating the calculation of rayscene intersections. SOBBs have the same memory footprint as the well-known oriented bounding boxes (OBB) and can be used with a similar ray intersection algorithm. We propose an efficient algorithm for constructing a BVH with SOBBs, using a transformation from a standard BVH built for axis-aligned bounding boxes (AABB). We use discrete orientation polytopes as a temporary bounding representation to find tightly fitting SOBBs. Additionally, we propose a compression scheme for SOBBs that makes their memory requirements comparable to those of AABBs. For secondary rays, the SOBB BVH provides a ray tracing speedup of 1.0-11.0x over the AABB BVH and it is 1.1x faster than the OBB BVH on average. The transformation of AABB BVH to SOBB BVH is, on average, 2.6x faster than the ditetrahedron-based AABB BVH to OBB BVH transformation.
Material Transforms from Disentangled NeRF Representations
(The Eurographics Association and John Wiley & Sons Ltd., 2025) Lopes, Ivan; Lalonde, Jean-François; Charette, Raoul de; Bousseau, Adrien; Day, Angela
In this paper, we first propose a novel method for transferring material transformations across different scenes. Building on disentangled Neural Radiance Field (NeRF) representations, our approach learns to map Bidirectional Reflectance Distribution Functions (BRDF) from pairs of scenes observed in varying conditions, such as dry and wet. The learned transformations can then be applied to unseen scenes with similar materials, therefore effectively rendering the transformation learned with an arbitrary level of intensity. Extensive experiments on synthetic scenes and real-world objects validate the effectiveness of our approach, showing that it can learn various transformations such as wetness, painting, coating, etc. Our results highlight not only the versatility of our method but also its potential for practical applications in computer graphics. We publish our method implementation, along with our synthetic/real datasets on https://github.com/astra-vision/BRDFTransform

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