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Laplacian Projection Based Global Physical Prior Smoke Reconstruction

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2024年第12期30卷 7657-7671页

作者： Xiao, Shibang Tong, Chao Zhang, Qifan Cen, Yunchi Li, Frederick W. B. Liang, Xiaohui Beihang Univ State Key Lab Virtual Real Technol & Syst Beijing 100191 Peoples R China Univ Durham Dept Comp Sci Durham DH1 3LE England Zhongguancun Lab Beijing 100086 Peoples R China

We present a novel framework for reconstructing fluid dynamics in real-life scenarios. Our approach leverages sparse view images and incorporates physical priors across long series of frames, resulting in reconstructed fluids with enhanced physical consistency. Unlike previous methods, we utilize a differentiable fluid simulator (DFS) and a differentiable renderer (DR) to exploit global physical priors, reducing reconstruction errors without the need for manual regularization coefficients. We introduce divergence-free Laplacian eigenfunctions (div-free LE) as velocity bases, improving computational efficiency and memory usage. By employing gradient-related strategies, we achieve better convergence and superior results. Extensive experiments demonstrate the effectiveness of our method, showcasing improved reconstruction quality and computational efficiency compared to existing approaches. We validate our approach using both synthetic and real data, highlighting its practical potential.

关键词： Fluids Image reconstruction Rendering (computer graphics) Optimization Laplace equations Eigenvalues and eigenfunctions computational efficiency computational geometry and object modeling computer graphics computing methodologies physically based modeling

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LFS-Aware Surface Reconstruction From Unoriented 3D Point Clouds

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IEEE TRANSACTIONS ON MULTIMEDIA 2024年 26卷 11415-11427页

作者： Fu, Rao Hormann, Kai Alliez, Pierre INRIA F-06902 Sohia Antipolis France Geometry Factory F-06560 Antibes France Univ Svizzera Italiana USI CH-6900 Lugano Switzerland

We present a novel approach for generating isotropic surface triangle meshes directly from unoriented 3D point clouds, with the mesh density adapting to the estimated local feature size (LFS). Popular reconstruction pipelines first reconstruct a dense mesh from the input point cloud and then apply remeshing to obtain an isotropic mesh. The sequential pipeline makes it hard to find a lower-density mesh while preserving more details. Instead, our approach reconstructs both an implicit function and an LFS-aware mesh sizing function directly from the input point cloud, which is then used to produce the final LFS-aware mesh without remeshing. We combine local curvature radius and shape diameter to estimate the LFS directly from the input point clouds. Additionally, we propose a new mesh solver to solve an implicit function whose zero level set delineates the surface without requiring normal orientation. The added value of our approach is generating isotropic meshes directly from 3D point clouds with an LFS-aware density, thus achieving a trade-off between geometric detail and mesh complexity. Our experiments also demonstrate the robustness of our method to noise, outliers, and missing data and can preserve sharp features for CAD point clouds.

关键词： Surface reconstruction Point cloud compression Three-dimensional displays Shape Estimation Surface fitting Scalability I.3.5 [Computing methodologies] computer graphics computational geometry and object modeling

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A Local Graph-Based Structure for Processing Gigantic Aggregated 3D Point Clouds

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2022年第8期28卷 2822-2833页

作者： Bletterer, Arnaud Payan, Frederic Antonini, Marc Univ Cote dAzur I3S CNRS Nice France

We present an original workflow for structuring a point cloud generated from several scans. Our representation is based on a set of local graphs. Each graph is constructed from the depth map provided by each scan. The graphs are then connected together via the overlapping areas, and careful consideration of the redundant points in these regions leads to a piecewise and globally consistent structure for the underlying surface sampled by the point cloud. The proposed workflow allows structuring aggregated point clouds, scan after scan, whatever the number of acquisitions and the number of points per acquisition, even on computers with very limited memory capacities. To show that our structure can be highly relevant for the community, where the gigantic amount of data represents a real scientific challenge per se, we present an algorithm based on this structure capable of resampling billions of points on standard computers. This application is particularly attractive for simplifying and visualizing gigantic point clouds representing very large-scale scenes (buildings, urban scenes, historical sites...), which often require a prohibitive number of points to describe them accurately.

关键词： Three-dimensional displays Surface morphology Random access memory Surface treatment Solid modeling Sensors Two dimensional displays computational geometry and object modeling three-dimensional graphics and realism 3D point clouds data structure graphs out-of-core algorithms poisson-disk sampling

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Scalable Contour Tree Computation by Data Parallel Peak Pruning

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2021年第4期27卷 2437-2454页

作者： Carr, Hamish A. Weber, Gunther H. Sewell, Christopher M. Rubel, Oliver Fasel, Patricia Ahrens, James P. Univ Leeds Leeds LS2 9JT W Yorkshire England Lawrence Berkeley Natl Lab Computat Res Div Berkeley CA 94720 USA Univ Calif Davis Dept Comp Sci Davis CA 95616 USA Los Alamos Natl Lab Los Alamos NM 87545 USA

As data sets grow to exascale, automated data analysis and visualization are increasingly important, to intermediate human understanding and to reduce demands on disk storage via in situ analysis. Trends in architecture of high performance computing systems necessitate analysis algorithms to make effective use of combinations of massively multicore and distributed systems. One of the principal analytic tools is the contour tree, which analyses relationships between contours to identify features of more than local importance. Unfortunately, the predominant algorithms for computing the contour tree are explicitly serial, and founded on serial metaphors, which has limited the scalability of this form of analysis. While there is some work on distributed contour tree computation, and separately on hybrid GPU-CPU computation, there is no efficient algorithm with strong formal guarantees on performance allied with fast practical performance. We report the first shared SMP algorithm for fully parallel contour tree computation, with formal guarantees of O(lg V lgt) parallel steps and O(V lg V) work for data with V samples and t contour tree supernodes, and implementations with more than 30x parallel speed up on both CPU using TBB and GPU using Thrust and up 70x speed up compared to the serial sweep and merge algorithm.

关键词： Topological analysis contour tree merge tree data parallel algorithms computer graphics computational geometry and object modeling curve surface solid and object representations simulation and modeling simulation output analysis

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PICO: Procedural Iterative Constrained Optimizer for Geometric modeling

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2021年第10期27卷 3968-3981页

作者： Krs, Vojtech Mech, Radomir Gaillard, Mathieu Carr, Nathan Benes, Bedrich Purdue Univ Dept Comp Graph Technol W Lafayette IN 47907 USA Adobe Res San Jose CA 95110 USA

Procedural modeling has produced amazing results, yet fundamental issues such as controllability and limited user guidance persist. We introduce a novel procedural model called PICO (Procedural Iterative Constrained Optimizer) and PICO-Graph that is the underlying procedural model designed with optimization in mind. The key novelty of PICO is that it enables the exploration of generative designs by combining both user and environmental constraints into a single framework by using optimization without the need to write procedural rules. The PICO-Graph procedural model consists of a set of geometry generating operations and a set of axioms connected in a directed cyclic graph. The forward generation is initiated by a set of axioms that use the connections to send coordinate systems and geometric objects through the PICO-Graph, which in turn generates more objects. This allows for fast generation of complex and varied geometries. Moreover, we combine PICO-Graph with efficient optimization that allows for quick exploration of the generated models and the generation of variants. The user defines the rules, the axioms, and the set of constraints;for example, whether an existing object should be supported by the generated model, whether symmetries exist, whether the object should spin, etc. PICO then generates a class of geometric models and optimizes them so that they fulfill the constraints. The generation and the optimization in our implementation provides interactive user control during model execution providing continuous feedback. For example, the user can sketch the constraints and guide the geometry to meet these specified goals. We show PICO on a variety of examples such as the generation of procedural chairs with multiple supports, generation of support structures for 3D printing, generation of spinning objects, or generation of procedural terrains matching a given input. Our framework could be used as a component in a larger design workflow;its strongest applica

关键词： Optimization geometry Shape computational modeling Grammar Three-dimensional displays Solid modeling computational geometry and object modeling three-dimensional graphics and realism

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A Shape Completion Component for Monocular Non-Rigid SLAM 18

A Shape Completion Component for Monocular Non-Rigid SLAM

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International Normal Labour and Birth Research Conference

作者： Su, Yongzhi Golyanik, Vladislav Minaskan, Nareg Ali, Sk Aziz Stricker, Didier TU Kaiserslautern DFKI Kaiserslautern Germany MPI Informat Saarbrucken Saarland Germany DFKI Kaiserslautern Germany

ISBN: (纸本)9781728147659

We propose a finite element method (FEM) based approach for surface stitching which can be integrated into existing SLAM and NRSfM pipelines for AR applications. Given individual reconstructions and camera poses at different time stamps, our stitching method incrementally completes the surface with a smooth transition between the hidden and the observed parts, so that all the observed parts can be stitched into a single surface. Thanks to the physical modelling, deformations from the observed parts are propagated to the hidden parts enabling an overall high-fidelity and realistic estimate. To keep the computational time in bounds, deformations near the observed parts are computed with FEM, and the remaining region is approximated by Laplacian deformation. We assume that no force is applied to the hidden parts. To evaluate the algorithm, we generate a synthetic dataset with ground truth. In our dataset, the camera observes only a part of the target surface in each frame and moves until the whole target surface is covered. The dataset which will be made publicly available includes the ground truth camera poses and geometries of the whole surface at each time frame. An experimental evaluation of the stitching method with accuracy metrics rounds out the draft.

关键词： H.5.1-Information Interfaces and Presentation Multimedia Information Systems Artificial, augmented, and virtual realities I.3.5 Computer Graphics computational geometry and object modeling Physically-based modeling

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A web system of virtual morphometric globes for Mars and the Moon

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PLANETARY AND SPACE SCIENCE 2018年第Sep.期159卷 105-109页

作者： Florinsky, I., V Garov, A. S. Karachevtseva, I. P. Russian Acad Sci Keldysh Inst Appl Math Inst Math Problems Biol Pushchino 142290 Moscow Region Russia Moscow State Univ Geodesy & Cartog MIIGAiK Extraterr Lab 4 Gorokhovsky Lane Moscow 105064 Russia

We developed a web system of virtual morphometric globes for Mars and the Moon. As the initial data, we used 15-arc-minutes gridded global digital elevation models (DEMs) extracted from the Mars Orbiter Laser Altimeter (MOLA) and the Lunar Orbiter Laser Altimeter (LOLA) gridded archives. We derived global digital models of sixteen morphometric variables including horizontal, vertical, minimal, and maximal curvatures, as well as catchment area and topographic index. The morphometric models were integrated into the web system developed as a distributed application consisting of a client front-end and a server back-end. The following main functions are implemented in the system: (1) selection of a morphometric variable;(2) two-dimensional visualization of a calculated global morphometric model;(3) 3D visualization of a calculated global morphometric model on the sphere surface;(4) change of a globe scale;and (5) globe rotation by an arbitrary angle. Free, real-time web access to the system is provided. The web system of virtual morphometric globes can be used for geological and geomorphological studies of Mars and the Moon at the global, continental, and regional scales.

关键词： Astronomy computational geometry and object modeling Earth and atmospheric sciences Three-dimensional graphics and realism

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A Benchmark for Distance Measurements 17

A Benchmark for Distance Measurements

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17th International Conference on Cyberworlds (CW)

作者： Krispel, Ulrich Fellner, Dieter W. Ullrich, Torsten Fraunhofer Austria Res GmbH Graz Austria Graz Univ Technol Graz Austria Tech Univ Darmstadt Darmstadt Germany Fraunhofer IGD Darmstadt Germany

ISBN: (纸本)9781538673157

The need to analyze and visualize distances between objects arises in many use cases. Although the problem to calculate the distance between two polygonal objects may sound simple, real-world scenarios with large models will always be challenging, but optimization techniques such as space partitioning can reduce the complexity of the average case significantly. Our contribution to this problem is a publicly available benchmark to compare distance calculation algorithms. Furthermore, we evaluated the two most important techniques (hierarchical tree structures versus grid-based approaches).

关键词： computational geometry and object modeling computer-aided design virtual reality benchmark distance measurements

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3D Navigation on Impossible Figures via Dynamically Reconfigurable Maze

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IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2016年第10期22卷 2275-2288页

作者： Lai, Chi-Fu William Yeung, Sai-Kit Yan, Xiaoqi Fu, Chi-Wing Tang, Chi-Keung Nanyang Technol Univ Sch Comp Engn Singapore Singapore Singapore Univ Technol & Design Singapore Singapore Chinese Univ Hong Kong Dept Comp Sci & Engn Hong Kong Hong Kong Peoples R China Hong Kong Univ Sci & Technol Dept Comp Sci & Engn Hong Kong Hong Kong Peoples R China

Previous research on impossible figures focuses extensively on single view modeling and rendering. Existing computer games that employ impossible figures as navigation maze for gaming either use a fixed third-person view with axonometric projection to retain the figure's impossibility perception, or simply break the figure's impossibility upon view changes. In this paper, we present a new approach towards 3D gaming with impossible figures, delivering for the first time navigation in 3D mazes constructed from impossible figures. Such result cannot be achieved by previous research work in modeling impossible figures. To deliver seamless gaming navigation and interaction, we propose i) a set of guiding principles for bringing out subtle perceptions and ii) a novel computational approach to construct 3D structures from impossible figure images and then to dynamically construct the impossible-figure maze subjected to user's view. In the end, we demonstrate and discuss our method with a variety of generic maze types.

关键词： computational geometry and object modeling impossible figure game dynamic and procedural modeling

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Projective Feature Learning for 3D Shapes with Multi-View Depth Images

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COMPUTER GRAPHICS FORUM 2015年第7期34卷 1-11页

作者： Xie, Zhige Xu, Kai Shan, Wen Liu, Ligang Xiong, Yueshan Huang, Hui SIAT Shenzhen VisuCA Key Lab Shenzhen Peoples R China Natl Univ Def Technol Sch Comp Beijing Peoples R China Univ Sci & Technol China Sch Math Sci Beijing Peoples R China

Feature learning for 3D shapes is challenging due to the lack of natural paramterization for 3D surface models. We adopt the multi-view depth image representation and propose Multi-View Deep Extreme Learning Machine (MVD-ELM) to achieve fast and quality projective feature learning for 3D shapes. In contrast to existing multi-view learning approaches, our method ensures the feature maps learned for different views are mutually dependent via shared weights and in each layer, their unprojections together form a valid 3D reconstruction of the input 3D shape through using normalized convolution kernels. These lead to a more accurate 3D feature learning as shown by the encouraging results in several applications. Moreover, the 3D reconstruction property enables clear visualization of the learned features, which further demonstrates the meaningfulness of our feature learning.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.5 [Computer Graphics]: modeling&mdash computational geometry and object modeling

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