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Modeling Crochet Patterns with a Force-directed Graph Layout
No full textDesigning crochet patterns is a difficult, time-consuming task. Typically, an initial pattern is created and crocheted; after seeing how the object comes out, the pattern is modified and some amount of stitches are undone and remade, through some number of iterations. This process involves a lot of guesswork and the manual labor of physically crocheting. In this paper, we present a way of creating a 3D representation of a crochet pattern using a written pattern as input: we translate the written pattern into a graph and obtain a force-directed graph layout. The result is a 3D model that looks like the hand-crocheted pattern in shape and size, with the advantage that the designer does not need to physically crochet the pattern and can make adjustments based on the digital model. Our intended audience includes both professional designers as well as beginners, helping designers visualize their crochet pattern before investing the time and effort to physically make it. While our application is oriented towards amigurumi, it could be extended to work with clothing or other similar styles of crochet.ACM/EG Expressive Symposium - WICED: Eurographics Workshop on Intelligent Cinematography and EditingUser Guided Creative Modelin
Geometry Compression Using Normal Uncertainty
No full textProgressive compression of triangle mesh geometry typically exploits spatial coherence to reduce data size while preserving surface detail. In applications where lossy compression is permissible, an effective strategy is to align distortion with the limitations of human visual perception-allocating more bits to perceptually sensitive regions and fewer where differences go unnoticed. This requires identifying surface regions where distortion would be most noticeable, a task often guided by perceptual metrics that approximate human judgment. Existing perceptual-driven progressive compression methods rely on these metrics to steer refinement, but doing so typically incurs additional data overhead to specify where each refinement occurs. We propose a novel progressive geometry compression algorithm that leverages a perceptually informed model of normal uncertainty to predict where distortion is most likely to be noticeable. This enables the encoder to focus refinements in those regions without explicitly transmitting their locations at each step, thereby reducing overhead. Compared to a baseline of Edgebreaker with weighed parallelogram prediction, our method produces reconstructions ranked higher by several established perceptual metrics. However, its high computational cost currently limits practical deployment.Computer Graphics and Visual Computing (CGVC)Geometry, Rendering, Animatio
Bringing Stones to Life: The First Digital 3D Library of Ancient Armenian Gravestones
No full textWe report the creation of a high-resolution 3D digital libraries of khachkars and tapanakars, ornately carved gravestones that offer a rare glimpse into the daily lives of ordinary Armenians during the Middle Ages. Khachkars are vertical stelae bearing ornate crosses and geometric motifs, while tapanakars feature a pyramidal form adorned with various everyday scenes such as horseback riding, dancing, trading, and communal feasting. Centuries of physical and environmental stress have threatened these carvings and no 3D digital records of them currently exist. Using photogrammetry and LiDAR scanning technologies, we have created fully rotatable 3D digital twins of over 70 tapanakars and 150 khachkars with the millimeter-level precision. These models capture the intricate carvings and iconography that traditional photography often misses, especially on weathered or lichen-covered surfaces. We also developed image processing steps to help convert barely visible carvings into their linear outlines enabling future epigraphic interpretation and the use of machine learning algorithms. Two dedicated websites have been created to make these 3D libraries publicly accessible and to allow scholars, students, and enthusiasts worldwide to explore their cultural and artistic significance across different interdisciplinary projects. These unique collections offer a valuable dataset for image processing and computer vision studies, such as pattern recognition, feature extraction, and 3D modeling techniques. Beyond academic use, this resource has potential applications in education, virtual exhibitions, and cultural tourism promoting Armenian cultural heritage on an international scale.Digital HeritageDigitization Tools and Application
Degenerancy-Resilient LIDAR Odometry via Reflectance-Dervied Correspondences
No full textThe key challenge in LiDAR odometry is estimating motion in geometrically degenerate environments, where standard geometrybased feature alignment often fails. LiDAR reflectance offers complementary information: it can be rendered as an image, letting the LiDAR to act like an active camera sensor and to add constraints where geometry is weak. We use these images to detect repeatable keypoints, match them across sweeps, and lift their locations to 3D, creating sparse and reflectance-informed correspondences. Our method follows a standard LiDAR-Inertial Odometry (LIO) pipeline. An Error-State Kalman Filter (ESKF) provides high-rate motion estimates for scan deskewing and for initializing ICP. We fuse reflectance-derived constraints into scan-to-map registration with a joint objective that combines a sparse point-to-point term with point-to-plane residuals, stabilizing motion directions that are otherwise weakly observable. We also select both reflectance and geometric correspondences to specifically constrain these weak directions. Experiments in geometrically degenerate and GNSS-denied settings, and even in presence of highly spatially anisotropic LiDAR acquisitions, show that adding reflectance-derived correspondences reduces drift and guides convergence toward the true pose.Smart Tools and Applications in Graphics - Eurographics Italian Chapter ConferenceRobotics and Mixed Realit
Lactea: Web-Based Spectrum-Preserving Multi-Resolution Visualization of the GAIA Star Catalog
No full textThe explosion of data in astronomy has resulted in an era of unprecedented opportunities for discovery. The GAIA mission's catalog, containing a large number of light sources (mostly stars) with several parameters such as sky position and proper motion, is playing a significant role in advancing astronomy research and has been crucial in various scientific breakthroughs over the past decade. In its current release, more than 200 million stars contain a calibrated continuous spectrum, which is essential for characterizing astronomical information such as effective temperature and surface gravity, and enabling complex tasks like interstellar extinction detection and narrow-band filtering. Even though numerous studies have been conducted to visualize and analyze the data in the SciVis and AstroVis communities, no work has attempted to leverage spectral information for visualization in real-time. Interactive exploration of such complex, massive data presents several challenges for visualization. This paper introduces a novel multi-resolution, spectrum-preserving data structure and a progressive, real-time visualization algorithm to handle the sheer volume of the data efficiently, enabling interactive visualization and exploration of the whole catalog's spectra. We show the efficiency of our method with our open-source, interactive, web-based tool for exploring the GAIA catalog, and discuss astronomically relevant use cases of our system.Computer Graphics ForumSpatial and Multi-Scale Data Visualizatio
Shape-Conditioned Human Motion Diffusion Model with Mesh Representation
No full textHuman motion generation is a key task in computer graphics. While various conditioning signals such as text, action class, or audio have been used to harness the generation process, most existing methods neglect the case where a specific body is desired to perform the motion. Additionally, they rely on skeleton-based pose representations, necessitating additional steps to produce renderable meshes of the intended body shape. Given that human motion involves a complex interplay of bones, joints, and muscles, focusing solely on the skeleton during generation neglects the rich information carried by muscles and soft tissues, as well as their influence on movement, ultimately limiting the variability and precision of the generated motions. In this paper, we introduce Shape-conditioned Motion Diffusion model (SMD), which enables the generation of human motion directly in the form of a mesh sequence, conditioned on both a text prompt and a body mesh. To fully exploit the mesh representation while minimizing resource costs, we employ spectral representation using the graph Laplacian to encode body meshes into the learning process. Unlike retargeting methods, our model does not require source motion data and generates a variety of desired semantic motions that is inherently tailored to the given identity shape. Extensive experimental evaluations show that the SMD model not only maintains the body shape consistently with the conditioning input across motion frames but also achieves competitive performance in text-to-motion and action-to-motion tasks compared to state-of-the-art methods.Computer Graphics ForumBringing Motion to Life: Motion Reconstruction and Control44
Iterative Lightmap Updates for Scene Editing
No full textLightmaps are popular for precomputed global illumination, but require costly recomputation when the scene changes. We present the theory and an iterative algorithm to update lightmaps efficiently, when objects are inserted or removed. Our method is based on path tracing, but focuses on updates to those paths that are affected by the scene change. Using an importance sampling scheme, our solution substantially accelerates convergence. Our GPU implementation is well-suited for interactive scene editing scenarios.Pacific Graphics Conference Papers, Posters, and DemosLighting & Renderin
TemPCC: Completing Temporal Occlusions in Large Dynamic Point Clouds captured by Multiple RGB-D Cameras
No full textWe present TemPCC, an approach to complete temporal occlusions in large dynamic point clouds. Our method manages a point set over time, integrates new observations into this set, and predicts the motion of occluded points based on the flow of surrounding visible ones. Unlike existing methods, our approach efficiently handles arbitrarily large point sets with linear complexity, does not reconstruct a canonical representation, and considers only local features. Our tests, performed on an Nvidia GeForce RTX 4090, demonstrate that our approach can complete a frame with 30,000 points in under 30 ms, while, in general, being able to handle point sets exceeding 1,000,000 points. This scalability enables the mitigation of temporal occlusions across entire scenes captured by multi-RGB-D camera setups. Our initial results demonstrate that self-occlusions are effectively completed and successfully generalized to unknown scenes despite limited training data.Eurographics 2025 - Short PapersShort Paper
Fast Planetary Shadows using Fourier-Compressed Horizon Maps
No full textShadows on large-scale terrains are important for many applications, including video games and scientific visualization. Yet real-time rendering of realistic soft shadows at planetary scale is a challenging task. Notably, many shadowing algorithms require keeping significant amounts of extra terrain geometry in memory to account for out-of-frustum occluders. We present Fourier-Compressed Horizon Mapping, an enhancement of the horizon mapping algorithm which is able to circumvent this requirement and render shadows in a single render pass. For a given digital elevation model, we create a compact representation of each pixel's horizon profile and use it to render soft shadows at runtime. This representation is based on a truncated Fourier series stored in a multi-resolution texture pyramid and can be encoded in a single four-channel 32 bit floating point texture. This makes this approach especially suitable for applications using a level-of-detail system for terrain rendering. By using a compact representation in frequency space, compressed horizon mapping consistently creates more accurate shadows compared to traditional horizon maps of the same memory footprint, while still running well at real-time frame rates.High-Performance Graphics - Symposium PapersReal-Time Renderin