11 results
Search Results
Now showing 1 - 10 of 11
Item FEMONUM: A Framework for Whole Body Pregnant Woman Modeling from Ante-Natal Imaging Data(The Eurographics Association, 2011) Alcalde, Juan Pablo de la Plata; Anquez, Jérémie; Bibin, Lazar; Boubekeur, Tamy; Angelini, Elsa; Bloch, Isabelle; K. Buehler and A. VilanovaAnatomical models of pregnant women can be used in several applications such as numerical dosimetry to assess the potential effects of electromagnetic fields on biological tissues, or medical simulations for delivery planning. Recent advances in medical imaging have enabled the generation of realistic and detailed models of human beings. This paper describes FEMONUM, a complete methodological framework for the construction of pregnant woman models based on medical images and their segmentation. FEMONUM combines several computer graphics methods, such as surface reconstruction and physics-based computer animation to model and deform pregnant women abdomens, to simulate different fetal positions and sizes and also different morphologies of the mother, represented with a synthetic woman body envelope. A set of 16 models, anatomically validated by clinical experts, is presented and is made available online to the scientific community. These models include detailed information on the utero-fetal units and cover different gestational stages with various fetal positions.Item GeoBrush: Interactive Mesh Geometry Cloning(The Eurographics Association and Blackwell Publishing Ltd., 2011) Takayama, Kenshi; Schmidt, Ryan; Singh, Karan; Igarashi, Takeo; Boubekeur, Tamy; Sorkine, Olga; M. Chen and O. DeussenWe propose a method for interactive cloning of 3D surface geometry using a paintbrush interface, similar to the continuous cloning brush popular in image editing. Existing interactive mesh composition tools focus on atomic copy-and-paste of pre-selected feature areas, and are either limited to copying surface displacements, or require the solution of variational optimization problems, which is too expensive for an interactive brush interface. In contrast, our GeoBrush method supports real-time continuous copying of arbitrary high-resolution surface features between irregular meshes, including topological handles. We achieve this by first establishing a correspondence between the source and target geometries using a novel generalized discrete exponential map parameterization. Next we roughly align the source geometry with the target shape using Green Coordinates with automaticallyconstructed cages. Finally, we compute an offset membrane to smoothly blend the pasted patch with C1 continuity before stitching it into the target. The offset membrane is a solution of a bi-harmonic PDE, which is computed on the GPU in real time by exploiting the regular parametric domain. We demonstrate the effectiveness of GeoBrush with various editing scenarios, including detail enrichment and completion of scanned surfaces.Item Proxy Clouds for RGB-D Stream Processing: A Preview(The Eurographics Association, 2017) Kaiser, Adrien; Zepeda, José Alonso Ybanez; Boubekeur, Tamy; Pierre Benard and Daniel SykoraModern consumer depth cameras are widely used for 3D capture in indoor environments, for applications such as modeling, robotics or gaming. Nevertheless, their use is limited by their low resolution, with frames often corrupted with noise, missing data and temporal inconsistencies. In order to cope with all these issues, we present Proxy Clouds, a multiplanar superstructure for real-time processing of RGB-D data. By generating a single set of planar proxies from raw RGB-D data and updating it through time, several processing primitives can be applied to improve the quality of the RGB-D stream or lighten further operations. We illustrate the use of Proxy Clouds on several applications, including noise and temporal flickering removal, hole filling, resampling, color processing and compression. We present experiments performed with our framework in indoor scenes of different natures captured with a consumer depth sensor.Item Interactive Monte-Carlo Ray-Tracing Upsampling(The Eurographics Association, 2016) Boughida, Malik; Groueix, Thibault; Boubekeur, Tamy; Luis Gonzaga Magalhaes and Rafal MantiukWe propose a practical method to approximate global illumination at interactive framerates for dynamic scenes. We address multi-bounce, visibility-aware indirect lighting, for diffuse to moderately glossy materials, relying on GPU-accelerated raytracing for this purpose. While Monte-Carlo ray-tracing algorithms offer unbiased results, they produce images which are, under interactive constraints, extremely noisy, even with GPU acceleration. Unfortunately, filtering them to reach visual appeal induces a large kernel, which is not compatible with interactive framerate. We address this problem using a simple downsampling approach. First, we trace indirect paths on a uniformly distributed subset of pixels, decorrelating diffuse and specular components of lighting. Then, we perform a joint bilateral upsampling on both components, taking inspiration from deferred shading by driving this upsampling with a full-resolution G-Buffer. Our solution provides smooth results, does not require any pre-computations, and is both easy to implement and flexible, as it can be used with any generation strategy for indirect rays.Item Automatic Line Handles for Freeform Deformation(The Eurographics Association, 2012) Schemali, Leïla; Thiery, Jean-Marc; Boubekeur, Tamy; Carlos Andujar and Enrico PuppoInteractive freeform surface deformation methods allow to explore the space of possible shapes using simple control structures. While recent advances in variational editing provide high quality deformations, designing control structures remains a time-consuming manual process. We propose a new automatic control structure generation based on the observation that the most salient visual structures of a surface, such as the one exploited in Line Drawing methods, are tightly linked to the potential deformations it may undergo. Our basic idea is to build control structures from those lines in order to provide users with an automatic set of deformation handles to grab and manipulate, avoiding the tedious task of region selection and handle positioning. The resulting interface inherits view-dependency and adaptivity from line definitions, reduces significantly the modeling session time in a number of scenarii, and remains fully compatible with classical handle-based deformations.Item A Survey on Cage-based Deformation of 3D Models(The Eurographics Association and John Wiley & Sons Ltd., 2024) Ströter, Daniel; Thiery, Jean-Marc; Hormann, Kai; Chen, Jiong; Chang, Qingjun; Besler, Sebastian; Mueller-Roemer, Johannes Sebastian; Boubekeur, Tamy; Stork, André; Fellner, Dieter W.; Aristidou, Andreas; Macdonnell, RachelInteractive deformation via control handles is essential in computer graphics for the modeling of 3D geometry. Deformation control structures include lattices for free-form deformation and skeletons for character articulation, but this report focuses on cage-based deformation. Cages for deformation control are coarse polygonal meshes that encase the to-be-deformed geometry, enabling high-resolution deformation. Cage-based deformation enables users to quickly manipulate 3D geometry by deforming the cage. Due to their utility, cage-based deformation techniques increasingly appear in many geometry modeling applications. For this reason, the computer graphics community has invested a great deal of effort in the past decade and beyond into improving automatic cage generation and cage-based deformation. Recent advances have significantly extended the practical capabilities of cage-based deformation methods. As a result, there is a large body of research on cage-based deformation. In this report, we provide a comprehensive overview of the current state of the art in cage-based deformation of 3D geometry. We discuss current methods in terms of deformation quality, practicality, and precomputation demands. In addition, we highlight potential future research directions that overcome current issues and extend the set of practical applications. In conjunction with this survey, we publish an application to unify the most relevant deformation methods. Our report is intended for computer graphics researchers, developers of interactive geometry modeling applications, and 3D modeling and character animation artists.Item A Survey on Data-driven Dictionary-based Methods for 3D Modeling(The Eurographics Association and John Wiley & Sons Ltd., 2018) Lescoat, Thibault; Ovsjanikov, Maks; Memari, Pooran; Thiery, Jean-Marc; Boubekeur, Tamy; Hildebrandt, Klaus and Theobalt, ChristianDictionaries are very useful objects for data analysis, as they enable a compact representation of large sets of objects through the combination of atoms. Dictionary-based techniques have also particularly benefited from the recent advances in machine learning, which has allowed for data-driven algorithms to take advantage of the redundancy in the input dataset and discover relations between objects without human supervision or hard-coded rules. Despite the success of dictionary-based techniques on a wide range of tasks in geometric modeling and geometry processing, the literature is missing a principled state-of-the-art of the current knowledge in this field. To fill this gap, we provide in this survey an overview of data-driven dictionary-based methods in geometric modeling. We structure our discussion by application domain: surface reconstruction, compression, and synthesis. Contrary to previous surveys, we place special emphasis on dictionary-based methods suitable for 3D data synthesis, with applications in geometric modeling and design. Our ultimate goal is to enlight the fact that these techniques can be used to combine the data-driven paradigm with design intent to synthesize new plausible objects with minimal human intervention. This is the main motivation to restrict the scope of the present survey to techniques handling point clouds and meshes, making use of dictionaries whose definition depends on the input data, and enabling shape reconstruction or synthesis through the combination of atoms.Item Efficient Point based Global Illumination on Intel MIC Architecture(The Eurographics Association, 2016) Xu, Xiang; Wang, Pei; Wang, Beibei; Wang, Lu; Tu, Changhe; Meng, Xiangxu; Boubekeur, Tamy; Luis Gonzaga Magalhaes and Rafal MantiukPoint-Based Global Illumination (PBGI) is a popular rendering method in special effects and motion picture productions. The tree-cut computation is in general the most time consuming part of this algorithm, but it can be formulated for efficient parallel execution, in particular regarding wide-SIMD hardware. In this context, we propose several vectorization schemes, namely single, packet and hybrid, to maximize the utilization of modern CPU architectures. While for the single scheme, 16 nodes from the hierarchy are processed for a single receiver in parallel, the packet scheme handles one node for 16 receivers. These two schemes work well for scenes having smooth geometry and diffuse material. When the scene contains high frequency bumps maps and glossy reflections, we use a hybrid vectorization method. We conduct experiments on an Intel Many Integrated Core architecture and report preliminary results on several scenes, showing that up to a 3x speedup can be achieved when compared with non-vectorized execution.Item Separable Approximation of Ambient Occlusion(The Eurographics Association, 2011) Huang, Jing; Boubekeur, Tamy; Ritschel, Tobias; Holländer, Matthias; Eisemann, Elmar; N. Avis and S. LefebvreAmbient occlusion (AO) provides an effective approximation to global illumination that enjoys widespread use amongst practitioners. In this paper, we present a fast easy-to-implement separable approximation to screen space ambient occlusion. Computing occlusion first along a single direction and then transporting this occlusion into a second pass that is stochastically evaluating the final shading based on the AO estimates proves extremely efficient. Combined with interleaved sampling and geometry-aware blur, visually convincing results close to a non-separable occlusion can be obtained at much higher performance.Item SimSelect: Similarity-based Selection for 3D Surfaces(The Eurographics Association and John Wiley and Sons Ltd., 2014) Guy, Emilie; Thiery, Jean-Marc; Boubekeur, Tamy; B. Levy and J. KautzSurface selection is one of the fundamental interactions in shape modeling. In the case of complex models, this task is often tedious for at least two reasons: firstly the local geometry of a given region may be hard to manually select and needs great accuracy; secondly the selection process may have to be repeated a large number of times for similar regions requiring similar subsequent editing. We propose SimSelect, a new system for interactive selection on 3D surfaces addressing these two issues. We cope with the accuracy issue by classifying selections in different types, namely components, parts and patches for which we independently optimize the selection process. Second, we address the repetitiveness issue by introducing an expansion process based on shape recognition which automatically retrieves potential selections similar to the user-defined one. As a result, our system provides the user with a compact set of simple interaction primitives providing a smooth select-and-edit workflow.