Browsing by Author "Rohmer, Damien"

Now showing 1 - 9 of 9
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    Collision Free Simplification for 2D Multi-Layered Shapes
    (The Eurographics Association, 2023) Gong, Xianjin; Parakkat, Amal Dev; Rohmer, Damien; Pelechano, Nuria; Liarokapis, Fotis; Rohmer, Damien; Asadipour, Ali
    We propose a simplification-aware untangling algorithm for 2D layered shapes stacked on each other. While the shape undergoes simplification, our approach adjusts the vertex positions to prevent collision with other layers while simultaneously maintaining the correct relative ordering and offsets between the layers. The method features a field-based representation of the shapes and extends the concept of "implicit untangling" by incorporating interleaved shape preservation through a parameterized shape-matching technique. Our approach can be plugged on top of any existing vertex-decimation approach, leveraging its localized nature to accelerate the field evaluation. Furthermore, our method can seamlessly handle an arbitrary number of stacked layers, making it a versatile solution for stacked garment simplification.
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    Deformation Grammars: Hierarchical Constraint Preservation Under Deformation
    (© 2017 The Eurographics Association and John Wiley & Sons Ltd., 2017) Vimont, Ulysse; Rohmer, Damien; Begault, Antoine; Cani, Marie‐Paule; Chen, Min and Zhang, Hao (Richard)
    Deformation grammars are a novel procedural framework enabling to sculpt hierarchical 3D models in an object‐dependent manner. They process object deformations as symbols thanks to user‐defined interpretation rules. We use them to define hierarchical deformation behaviours tailored for each model, and enabling any sculpting gesture to be interpreted as some adapted constraint‐preserving deformation. A variety of object‐specific constraints can be enforced using this framework, such as maintaining distributions of subparts, avoiding self‐penetrations or meeting semantic‐based user‐defined rules. The operations used to maintain constraints are kept transparent to the user, enabling them to focus on their design. We demonstrate the feasibility and the versatility of this approach on a variety of examples, implemented within an interactive sculpting system.Deformation grammars are a novel procedural framework enabling to sculpt hierarchical 3D models in an object‐dependent manner. They process object deformations as symbols thanks to user‐defined interpretation rules. We use them to define hierarchical deformation behaviours tailored for each model,.
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    Fashion Transfer: Dressing 3D Characters from Stylized Fashion Sketches
    (© 2021 Eurographics ‐ The European Association for Computer Graphics and John Wiley & Sons Ltd, 2021) Fondevilla, Amelie; Rohmer, Damien; Hahmann, Stefanie; Bousseau, Adrien; Cani, Marie‐Paule; Benes, Bedrich and Hauser, Helwig
    Fashion design often starts with hand‐drawn, expressive sketches that communicate the essence of a garment over idealized human bodies. We propose an approach to automatically dress virtual characters from such input, previously complemented with user‐annotations. In contrast to prior work requiring users to draw garments with accurate proportions over each virtual character to be dressed, our method follows a style transfer strategy : the information extracted from a single, annotated fashion sketch can be used to inform the synthesis of one to many new garment(s) with similar style, yet different proportions. In particular, we define the style of a loose garment from its silhouette and folds, which we extract from the drawing. Key to our method is our strategy to extract both shape and repetitive patterns of folds from the 2D input. As our results show, each input sketch can be used to dress a variety of characters of different morphologies, from virtual humans to cartoon‐style characters.
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    Generating Upper-Body Motion for Real-Time Characters Making their Way through Dynamic Environments
    (The Eurographics Association and John Wiley & Sons Ltd., 2022) Alvarado, Eduardo; Rohmer, Damien; Cani, Marie-Paule; Dominik L. Michels; Soeren Pirk
    Real-time character animation in dynamic environments requires the generation of plausible upper-body movements regardless of the nature of the environment, including non-rigid obstacles such as vegetation. We propose a flexible model for upper-body interactions, based on the anticipation of the character's surroundings, and on antagonistic controllers to adapt the amount of muscular stiffness and response time to better deal with obstacles. Our solution relies on a hybrid method for character animation that couples a keyframe sequence with kinematic constraints and lightweight physics. The dynamic response of the character's upper-limbs leverages antagonistic controllers, allowing us to tune tension/relaxation in the upper-body without diverging from the reference keyframe motion. A new sight model, controlled by procedural rules, enables high-level authoring of the way the character generates interactions by adapting its stiffness and reaction time. As results show, our real-time method offers precise and explicit control over the character's behavior and style, while seamlessly adapting to new situations. Our model is therefore well suited for gaming applications.
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    IMET 2023: Frontmatter
    (The Eurographics Association, 2023) Pelechano, Nuria; Liarokapis, Fotis; Rohmer, Damien; Asadipour, Ali; Pelechano, Nuria; Liarokapis, Fotis; Rohmer, Damien; Asadipour, Ali
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    Progressive and Efficient Multi-Resolution Representations for Brain Tractograms
    (The Eurographics Association, 2018) Mercier, Corentin; Gori, Pietro; Rohmer, Damien; Cani, Marie-Paule; Boubekeur, Tamy; Thiery, Jean-Marc; Bloch, Isabelle; Puig Puig, Anna and Schultz, Thomas and Vilanova, Anna and Hotz, Ingrid and Kozlikova, Barbora and Vázquez, Pere-Pau
    Current tractography methods generate tractograms composed of millions of 3D polylines, called fibers, making visualization and interpretation extremely challenging, thus complexifying the use of this technique in a clinical environment. We propose to progressively simplify tractograms by grouping similar fibers into generalized cylinders. This produces a fine-grained multiresolution model that provides a progressive and real-time navigation through different levels of detail. This model preserves the overall structure of the tractogram and can be adapted to different measures of similarity. We also provide an efficient implementation of the method based on a Delaunay tetrahedralization. We illustrate our method using the Human Connectome Project dataset.
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    Robust Pointset Denoising of Piecewise-Smooth Surfaces through Line Processes
    (The Eurographics Association and John Wiley & Sons Ltd., 2023) Wei, Jiayi; Chen, Jiong; Rohmer, Damien; Memari, Pooran; Desbrun, Mathieu; Myszkowski, Karol; Niessner, Matthias
    Denoising is a common, yet critical operation in geometry processing aiming at recovering high-fidelity models of piecewisesmooth objects from noise-corrupted pointsets. Despite a sizable literature on the topic, there is a dearth of approaches capable of processing very noisy and outlier-ridden input pointsets for which no normal estimates and no assumptions on the underlying geometric features or noise type are provided. In this paper, we propose a new robust-statistics approach to denoising pointsets based on line processes to offer robustness to noise and outliers while preserving sharp features possibly present in the data. While the use of robust statistics in denoising is hardly new, most approaches rely on prescribed filtering using data-independent blending expressions based on the spatial and normal closeness of samples. Instead, our approach deduces a geometric denoising strategy through robust and regularized tangent plane fitting of the initial pointset, obtained numerically via alternating minimizations for efficiency and reliability. Key to our variational approach is the use of line processes to identify inliers vs. outliers, as well as the presence of sharp features. We demonstrate that our method can denoise sampled piecewise-smooth surfaces for levels of noise and outliers at which previous works fall short.
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    SoftWalks: Real-Time, Two-Ways Interaction between a Character and Loose Grounds
    (The Eurographics Association, 2021) Paliard, Chloé; Alvarado, Eduardo; Rohmer, Damien; Cani, Marie-Paule; Theisel, Holger and Wimmer, Michael
    When walking on loose terrains, possibly covered with vegetation, the ground and grass should deform, but the character's gait should also change accordingly.We propose a method for modeling such two-ways interactions in real-time.We first complement a layered character model by a high-level controller, which uses position and angular velocity inputs to improve dynamic oscillations when walking on various slopes. Secondly, at a refined level, the feet are set to locally deform the ground and surrounding vegetation using efficient procedural functions, while the character's response to such deformations is computed through adapted inverse kinematics. While simple to set up, our method is generic enough to adapt to any character morphology. Moreover, its ability to generate in real time, consistent gaits on a variety of loose grounds of arbitrary slope, possibly covered with grass, makes it an interesting solution to enhance films and games.
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    Velocity Skinning for Real-time Stylized Skeletal Animation
    (The Eurographics Association and John Wiley & Sons Ltd., 2021) Rohmer, Damien; Tarini, Marco; Kalyanasundaram, Niranjan; Moshfeghifar, Faezeh; Cani, Marie-Paule; Zordan, Victor; Mitra, Niloy and Viola, Ivan
    Secondary animation effects are essential for liveliness. We propose a simple, real-time solution for adding them on top of standard skinning, enabling artist-driven stylization of skeletal motion. Our method takes a standard skeleton animation as input, along with a skin mesh and rig weights. It then derives per-vertex deformations from the different linear and angular velocities along the skeletal hierarchy. We highlight two specific applications of this general framework, namely the cartoonlike ''squashy'' and ''floppy'' effects, achieved from specific combinations of velocity terms. As our results show, combining these effects enables to mimic, enhance and stylize physical-looking behaviours within a standard animation pipeline, for arbitrary skinned characters. Interactive on CPU, our method allows for GPU implementation, yielding real-time performances even on large meshes. Animator control is supported through a simple interface toolkit, enabling to refine the desired type and magnitude of deformation at relevant vertices by simply painting weights. The resulting rigged character automatically responds to new skeletal animation, without further input.