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Regression-Based Landmark Detection on Dynamic Human Models

computer graphics FORUM 2017年第7期36卷 73-82页

作者： Jang, Deok-Kyeong Lee, Sung-Hee Korea Adv Inst Sci & Technol Daejeon South Korea

Detecting anatomical landmarks on various human models with dynamic poses remains an important and challenging problem in computer graphics research. We present a novel framework that consists of two-level regressors for finding correlations between human shapes and landmark positions in both body part and holistic scales. To this end, we first develop pose invariant coordinates of landmarks that represent both local and global shape features by using the pose invariant local shape descriptors and their spatial relationships. Our body part-level regression deals with the shape features from only those body parts that correspond to a certain landmark. In order to do this, we develop a method that identifies such body parts per landmark, by using geometric shape dictionary obtained through the bag of features method. Our method is nearly automatic, as it requires human assistance only once to differentiate the left and right sides. The method also shows the prediction accuracy comparable to or better than those of existing methods, with a test data set containing a large variation of human shapes and poses.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.5 [computer graphics]: Computational Geometry and Object Modeling—Geometric algorithms languages and systems

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Albero: A Visual Analytics Approach for Probabilistic Weather Forecasting

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computer graphics FORUM 2017年第7期36卷 135-144页

作者： Diehl, A. Pelorosso, L. Delrieux, C. Matkovic, K. Ruiz, J. Groeller, M. E. Bruckner, S. Univ Konstanz Constance Germany Univ Buenos Aires Buenos Aires DF Argentina South Natl Univ Bahia Blanca Buenos Aires Argentina VRVis Res Ctr Vienna Austria UBA CONICET CIMA DCAOFCEN Buenos Aires DF Argentina Vienna Univ Technol Vienna Austria Univ Bergen Bergen Norway

Probabilistic weather forecasts are amongst the most popular ways to quantify numerical forecast uncertainties. The analog regression method can quantify uncertainties and express them as probabilities. The method comprises the analysis of errors from a large database of past forecasts generated with a specific numerical model and observational data. Current visualization tools based on this method are essentially automated and provide limited analysis capabilities. In this paper, we propose a novel approach that breaks down the automatic process using the experience and knowledge of the users and creates a new interactive visual workflow. Our approach allows forecasters to study probabilistic forecasts, their inner analogs and observations, their associated spatial errors, and additional statistical information by means of coordinated and linked views. We designed the presented solution following a participatory methodology together with domain experts. Several meteorologists with different backgrounds validated the approach. Two case studies illustrate the capabilities of our solution. It successfully facilitates the analysis of uncertainty and systematic model biases for improved decision-making and process-quality measurements.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.3 [computer graphics]: Picture/Image Generation—Viewing algorithms I.3.6 [computer graphics]: Methodology and Techniques—Interaction techniques I.3.8 [computer graphics]: applications—Probabilistic Weather Forecasting

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Photometric Stabilization for Fast-forward Videos

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computer graphics FORUM 2017年第7期36卷 105-113页

作者： Zhang, Xuaner Lee, Joon-Young Sunkavalli, Kalyan Wang, Zhaowen Univ Calif Berkeley Berkeley CA 94720 USA Adobe Res San Jose CA USA

Videos captured by consumer cameras often exhibit temporal variations in color and tone that are caused by camera auto-adjustments like white-balance and exposure. When such videos are sub-sampled to play fast-forward, as in the increasingly popular forms of timelapse and hyperlapse videos, these temporal variations are exacerbated and appear as visually disturbing high frequency flickering. Previous techniques to photometrically stabilize videos typically rely on computing dense correspondences between video frames, and use these correspondences to remove all color changes in the video sequences. However, this approach is limited in fast-forward videos that often have large content changes and also might exhibit changes in scene illumination that should be preserved. In this work, we propose a novel photometric stabilization algorithm for fast-forward videos that is robust to large content-variation across frames. We compute pairwise color and tone transformations between neighboring frames and smooth these pair-wise transformations while taking in account the possibility of scene/content variations. This allows us to eliminate high-frequency fluctuations, while still adapting to real variations in scene characteristics. We evaluate our technique on a new dataset consisting of controlled synthetic and real videos, and demonstrate that our techniques outperforms the state-of-the-art.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.3 [computer graphics]: Picture/Image Generation—Display algorithms I.4.3 [Image Processing and computer Vision]: Enhancement—Smoothing

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Storage and Processing Technologies of Cognitive Content for eLearning Systems

Storage and Processing Technologies of Cognitive Content for...

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Russia and pacific conference on computer Technology and applications (RPC)

作者： S.V. Tarkhov N.S. Minasova Sh.M. Minasov L.M. Tarkhova Department of Computer Science Ufa State Aviation Technical University Ufa Russia Department of Mechanics and Engineering Graphics Bashkir State Agrarian University Ufa Russia

ISBN: (纸本)9781538675328

Described the technologies of structuring, decomposition, storage organization and personal-oriented assembly of training content in web-oriented open eLearning systems. Hierarchical object-oriented model allows to store decomposed to low-level data and perform automated reconstruction cognitive content provided to trainee in the compiled modules form, that contain training materials and management procedures adaptive eLearning. The technology is used for virtual knowledge space building.

关键词： Electronic learning Training Metadata Shape Object oriented modeling Adaptation models

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Patch2Vec: Globally Consistent Image Patch Representation

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computer graphics FORUM 2017年第7期36卷 183-194页

作者： Fried, O. Avidan, S. Cohen-Or, D. Princeton Univ Princeton NJ 08544 USA Tel Aviv Univ Tel Aviv Israel

Many image editing applications rely on the analysis of image patches. In this paper, we present a method to analyze patches by embedding them to a vector space, in which the Euclidean distance reflects patch similarity. Inspired by Word2Vec, we term our approach Patch2Vec. However, there is a significant difference between words and patches. Words have a fairly small and well defined dictionary. Image patches, on the other hand, have no such dictionary and the number of different patch types is not well defined. The problem is aggravated by the fact that each patch might contain several objects and textures. Moreover, Patch2Vec should be universal because it must be able to map never-seen-before texture to the vector space. The mapping is learned by analyzing the distribution of all natural patches. We use Convolutional Neural Networks (CNN) to learn Patch2Vec. In particular, we train a CNN on labeled images with a triplet-loss objective function. The trained network encodes a given patch to a 128D vector. Patch2Vec is evaluated visually, qualitatively, and quantitatively. We then use several variants of an interactive single-click image segmentation algorithm to demonstrate the power of our method.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.4.10 [Image Processing and computer Vision]: Image Representation—Multidimensional

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Group Representation of Global Intrinsic Symmetries

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computer graphics FORUM 2017年第7期36卷 51-61页

作者： Wang, Hui Huang, Hui Shijiazhuang Tiedao Univ Sch Informat Sci & Technol Shijiazhuang Hebei Peoples R China Shenzhen Univ Coll Comp Sci & Software Engn Shenzhen Peoples R China

Global intrinsic symmetry detection of 3D shapes has received considerable attentions in recent years. However, unlike extrinsic symmetry that can be represented compactly as a combination of an orthogonal matrix and a translation vector, representing the global intrinsic symmetry itself is still challenging. Most previous works based on point-to-point representations of global intrinsic symmetries can only find reflectional symmetries, and are inadequate for describing the structure of a global intrinsic symmetry group. In this paper, we propose a novel group representation of global intrinsic symmetries, which describes each global intrinsic symmetry as a linear transformation of functional space on shapes. If the eigenfunctions of the Laplace-Beltrami operator on shapes are chosen as the basis of functional space, the group representation has a block diagonal structure. We thus prove that the group representation of each symmetry can be uniquely determined from a small number of symmetric pairs of points under certain conditions, where the number of pairs is equal to the maximum multiplicity of eigenvalues of the Laplace-Beltrami operator. Based on solid theoretical analysis, we propose an efficient global intrinsic symmetry detection method, which is the first one able to detect all reflectional and rotational global intrinsic symmetries with a clear group structure description. Experimental results demonstrate the effectiveness of our approach.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.5 [computer graphics]: computer graphics/Computational Geometry and Object Modeling—[Geometric algorithms languages and systems]

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Modeling, Evaluation and Optimization of Interlocking Shell Pieces

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computer graphics FORUM 2017年第7期36卷 1-13页

作者： Yao, Miaojun Chen, Zhili Xu, Weiwei Wang, Huamin Ohio State Univ Columbus OH 43210 USA Adobe Res San Jose CA USA Zhejiang Univ Hangzhou Zhejiang Peoples R China

While the 3D printing technology has become increasingly popular in recent years, it suffers from two critical limitations: expensive printing material and long printing time. An effective solution is to hollow the 3D model into a shell and print the shell by parts. Unfortunately, making shell pieces tightly assembled and easy to disassemble seem to be two contradictory conditions, and there exists no easy way to satisfy them at the same time yet. In this paper, we present a computational system to design an interlocking structure of a partitioned shell model, which uses only male and female connectors to lock shell pieces in the assembled configuration. Given a mesh segmentation input, our system automatically finds an optimal installation plan specifying both the installation order and the installation directions of the pieces, and then builds the models of the shell pieces using optimized shell thickness and connector sizes. To find the optimal installation plan, we develop simulation-based and data-driven metrics, and we incorporate them into an optimal plan search algorithm with fast pruning and local optimization strategies. The whole system is automatic, except for the shape design of the key piece. The interlocking structure does not introduce new gaps on the outer surface, which would become noticeable inevitably due to limited printer precision. Our experiment shows that the assembled object is strong against separation, yet still easy to disassemble.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.5 [computer graphics]: Computational Geometry and Object Modeling—Physically based modeling

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Data-Driven Sparse Priors of 3D Shapes

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computer graphics FORUM 2017年第7期36卷 63-72页

作者： Remil, O. Xie, Q. Xie, X. Xu, K. Wang, J. Nanjing Univ Aeronaut & Astronaut Nanjing Jiangsu Peoples R China Ecole Mil Polytech Bordj El Bahri Algeria Natl Univ Def Technol Changsha Hunan Peoples R China Chuzhou Univ Chuzhou Anhui Peoples R China

We present a sparse optimization framework for extracting sparse shape priors from a collection of 3D models. Shape priors are defined as point-set neighborhoods sampled from shape surfaces which convey important information encompassing normals and local shape characterization. A 3D shape model can be considered to be formed with a set of 3D local shape priors, while most of them are likely to have similar geometry. Our key observation is that the local priors extracted from a family of 3D shapes lie in a very low-dimensional manifold. Consequently, a compact and informative subset of priors can be learned to efficiently encode all shapes of the same family. A comprehensive library of local shape priors is first built with the given collection of 3D models of the same family. We then formulate a global, sparse optimization problem which enforces selecting representative priors while minimizing the reconstruction error. To solve the optimization problem, we design an efficient solver based on the Augmented Lagrangian Multipliers method (ALM). Extensive experiments exhibit the power of our data-driven sparse priors in elegantly solving several high-level shape analysis applications and geometry processing tasks, such as shape retrieval, style analysis and symmetry detection.

关键词： Categories and Subject Descriptors (according to ACM CCS) I.3.5 [computer graphics]: Computational Geometry and Object Modeling—Geometric algorithms languages and systems

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applications of Graph Theory

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PROCEEDINGS OF THE IEEE 2018年第5期106卷 784-786页

作者： Adali, Tuelay Ortega, Antonio Univ Maryland Baltimore Cty Baltimore MD 21228 USA Univ Maryland Baltimore Cty Dept Comp Sci & Elect Engn Baltimore MD 21228 USA Univ Southern Calif Elect Engn Dept Los Angeles CA USA USC EE Syst Los Angeles CA USA USC Signal & Image Proc Inst Los Angeles CA USA

Graph-theoretical methods are being increasingly used in areas of interest within the IEEE and beyond. Graphs are mathematical abstractions that can be used to represent networks of various types: physical (e.g., the internet or electrical networks), biological (e.g., brain networks), or social (e.g., online social networks). Furthermore, graphs can provide tools for flexible representation of data sets in which data points have irregular positions with respect to each other. Common examples of this include data sets acquired by a sensor network, where uniform sensor placement may not be possible, or machine learning data sets, where training samples are not uniformly distributed in feature space. In some instances, a graph representation arises as a natural way to describe the problem, while in other areas, e.g., image processing, they are being used to develop powerful, content-dependent alternatives to conventional processing tools.

关键词： Special issues and sections Graph theory computer graphics Image processing Machine learning Training data Combinatorial mathematics

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Computing restricted Voronoi diagram on graphics hardware 25

Computing restricted Voronoi diagram on graphics hardware

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25th pacific conference on computer graphics and applications, pacific graphics 2017

作者： Han, Jiawei Yan, Dong-Ming Wang, Lili Zhao, Qinping State Key Laboratory of Virtual Reality Technology and Systems School of Computer Science and Engineering Beihang University China National Laboratory of Pattern Recognition Institute of Automation Chinese Academy of Sciences China

ISBN: (纸本)9783038680512

The 3D restricted Voronoi diagram (RVD), defined as the intersection of the 3D Voronoi diagram of a pointset with a mesh surface, has many applications in geometry processing. There exist several CPU algorithms for computing RVDs. However, such algorithms still cannot compute RVDs in realtime. In this short paper, we propose an efficient algorithm for computing RVDs on graphics hardware. We demonstrate the robustness and the efficiency of the proposed GPU algorithm by applying it to surface remeshing based on centroidal Voronoi tessellation. © 2017 The Author(s) Eurographics Proceedings © 2017 The Eurographics Association.

关键词： Computational geometry

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