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Efficient Edit Propagation Using hierarchical data structure

IEEE TRANSACTIONS ON VISUALIZATION AND COMPUTER GRAPHICS 2011年第8期17卷 1135-1147页

作者： Xiao, Chunxia Nie, Yongwei Tang, Feng Wuhan Univ Sch Comp Wuhan 430072 Peoples R China MIUL HP Labs Palo Alto CA 94304 USA

This paper presents a novel unified hierarchical structure for scalable edit propagation. Our method is based on the key observation that in edit propagation, appearance varies very smoothly in those regions where the appearance is different from the user-specified pixels. Uniformly sampling in these regions leads to redundant computation. We propose to use a quadtree-based adaptive subdivision method such that more samples are selected in similar regions and less in those that are different from the user-specified regions. As a result, both the computation and the memory requirement are significantly reduced. In edit propagation, an edge-preserving propagation function is first built, and the full solution for all the pixels can be computed by interpolating from the solution obtained from the adaptively subdivided domain. Furthermore, our approach can be easily extended to accelerate video edit propagation using an adaptive octree structure. In order to improve user interaction, we introduce several new Gaussian Mixture Model (GMM) brushes to find pixels that are similar to the user-specified regions. Compared with previous methods, our approach requires significantly less time and memory, while achieving visually same results. Experimental results demonstrate the efficiency and effectiveness of our approach on high-resolution photographs and videos.

关键词： Tone adjustment Gaussian mixture model hierarchical data structure high dynamic range imaging tone mapping

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A new hierarchical triangle-based point-in-polygon data structure

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COMPUTERS & GEOSCIENCES 2009年第9期35卷 1843-1853页

作者： Jimenez, Juan J. Feito, Francisco R. Segura, Rafael J. Univ Jaen Dept Informat E-23071 Jaen Spain

The point-in-polygon or containment test is fundamental in computational geometry and is applied intensively in geographical information systems. When this test is repeated several times with the same polygon a data structure is necessary in order to reduce the linear time needed to obtain an inclusion result. In the literature different approaches, like grids or quadtrees, have been proposed for reducing the complexity of these algorithms. We propose a new data structure based on hierarchical subdivisions by means of tri-cones, which reduces the time necessary for this inclusion test. This data structure, named tri-tree, decomposes the whole space by means of tri-cones and classifies the edges of the polygon. For the inclusion test only the edges classified in one tri-cone are considered. The tri-tree has a set of properties which makes it specially suited to this aim, with a similar complexity to other data structures, but well suited to polygons which represent regions. We include a theoretical and practical study in which the new data structure is compared with classical ones, showing a significant improvement. (c) 2009 Elsevier Ltd. All rights reserved.

关键词： Inclusion test Geometric algorithms Computer graphics Geographical information systems hierarchical data structure Spatial decomposition

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ALGORITHMS FOR CALCULATING MULTICHANNEL IMAGE HISTOGRAMS USING hierarchical data structureS

COMPUTER OPTICS

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COMPUTER OPTICS 2016年第4期40卷 535-542页

作者： Denisova, A. Y. Sergeyev, V. V. Samara Natl Res Univ Samara Russia RAS Branch FSRC Crystallog & Photon Image Proc Syst Inst Samara Russia

In the article we offer a novel approach to calculating multichannel image histograms using hierarchical data structures. The proposed methods result in a histogram-tree which has many advantages over existing data structures traditionally used for multidimensional histograms. The suggested data structure requires a significantly smaller memory space for storage in comparison with a histogram that is presented as a frequency table for all possible brightness values (histogram-hypercube). The histogram-tree provides a dramatic decrease in speed in comparison with the list of unique brightness values and their frequencies (histogram-list). Moreover, the histogram-tree allows one to approximate the probabilities of brightness values which are not presented in the analyzed image in contrast with the histogram-list. The possibility of histogram approximation is very important for practical applications. Such approximation for histogram-tree is constructed by means of tree reduction. Nodes with frequencies lower than a given threshold are removed from the histogram-tree. The reduced histogram-tree benefits from the decrease of the required memory space while maintaining the accuracy of the original probability density distribution representation. We propose two algorithms for constructing a histogram-tree. The "depth" algorithm operates with image pixels sequentially. For each pixel it constructs appropriate branches and nodes until the maximum depth of the tree is achieved. This algorithm has a recursive realization and is more time efficient than the other one. The "across" algorithm performs a multiple scan of the image, each time filling just one tree level. This algorithm allows one to operate with images with a larger number of channels than the "depth" algorithm because it is more memory efficient in the runtime when approximating a histogram. Both algorithms build the histogram-tree significantly faster when compared with the construction of the histogram-list. Th

关键词： multichannel images histogram linked list hierarchical data structure non- balanced tree

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A hierarchical radiosity platform using efficient data structures and VRML 97

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COMPUTER NETWORKS AND ISDN SYSTEMS 1998年第20-21期30卷 1961-1974页

作者： Kardassevitch, C Paulin, M Jessel, JP Caubet, R IRIT UPS F-31062 Toulouse France

The constant growth of hierarchical radiosity (HR) model number and complexity, leads us into defining a well-balanced platform, answering to the diversity of their exigencies. In this paper, we present new hierarchical data structures: partitioning trees and meta-hierarchies, They allow one to elaborate local and autonomous hierarchies (crucial in the use of pre-computed hierarchical objects and dynamic radiosity models), and permit one to economize significant memory space, and at a lower level, CPU resources. We will show how using VRML 97 language answers, in an efficient and universal way, to the requirement of data storage, environment description, and interactive visualization for HR. (C) 1998 Elsevier Science B.V. All rights reserved.

关键词： computer graphics global illumination hierarchical radiosity VRML 97 hierarchical data structure

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Correlations of Permeability and Geological Characteristics Based on Mercury Intrusion data and hierarchical Statistical Models: A Case Study

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JOURNAL OF ENERGY RESOURCES TECHNOLOGY-TRANSACTIONS OF THE ASME 2020年第12期142卷 123004页

作者： Li, Zihao Gao, Wenyu Li, Xiangming Virginia Tech Dept Min & Minerals Engn Blacksburg VA 24060 USA Virginia Tech Dept Stat Blacksburg VA 24060 USA Virginia Tech Stat Applicat & Innovat Grp SAIG Blacksburg VA 24060 USA Yangtze Univ Coll Geosci Wuhan 430100 Hubei Peoples R China Hubei Cooperat Innovat Ctr Unconvent Oil & Gas Wuhan 430100 Hubei Peoples R China

The mercury intrusion technique is a crucial in-lab method to investigate the porous medium properties. The potentiality of mercury intrusion data has not been explored significantly in the traditional interpretation. Thus, a hierarchical statistical model that not only captures the quantitative relationship between petrophysical properties but also accounts for different geological members is developed to interpret mercury intrusion data. This multilevel model is established from almost 800 samples with specific geological characteristics. We distinguish the fixed effects and the random effects in this mixed model. The overall connection between the selected petrophysical parameters is described by the fixed effects at a higher level, while variations due to different geological members are accommodated as the random effects at a lower level. The selected petrophysical parameters are observed through hypothesis testing and model selection. In this case study, five petrophysical parameters are selected into the model. Essential visualizations are also provided to assist the interpretations of the probabilistically model. The final model reveals the quantitative relationship between permeability and other petrophysical properties in each member and the order of relative importance for each property. With this studied relationship and advanced model, the geological reservoir simulation can be greatly detailed and accurate in the future.

关键词： geological member hierarchical data structure petrophysical properties mercury intrusion data oil gas reservoirs petroleum engineering

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G¹ hierarchical Bezier surface over arbitrary meshes

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COMPUTER GRAPHICS FORUM 1999年第4期18卷 223-236页

作者： Bercovier, M Volpin, O Hebrew Univ Jerusalem Inst Comp Sci Jerusalem Israel

This paper presents a method for constructing composite surfaces based on a collection of quadrilateral parches. A global parameterization using bilinear quadrilateral meshes and FEM like,minimization procedure are introduced. Smoothing conditions such as C-1 and G(1) arehandled by constraint equation and a related duality argument is implemented. The surfaces that can be constructed in this way, include conforming and non-conforming connections (3 less than or equal to n less than or equal to 6, T-nodes) between elementary patches. Non-manifold surfaces are automatically treated also by this data structure. The underlying quadratic programming with linear constraints is solved by duality methods. hierarchical data structure with bordering matrices methods are implemented to deal with local refinement (subdivision). The present work details the actual implementation for the case of Bezier patches.

关键词： finite element method (FEM) local refinement hierarchical data structure duality, minimization under constraints

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On levels of detail in terrains

GRAPHICAL MODELS AND IMAGE PROCESSING

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GRAPHICAL MODELS AND IMAGE PROCESSING 1998年第1期60卷 1-12页

作者： de Berg, M Dobrindt, KTG Univ Utrecht Dept Comp Sci NL-3508 TB Utrecht Netherlands

In many applications it is important that one view a scene at different levels of detail. A prime example is flight simulation. A high level of detail is needed when flying low whereas a low level of detail suffices when flying high. More precisely, one would like to visualize the part of the scene that is close at a high level of detail and the part that is far away at a low level of detail. We propose a hierarchy of detail levels for a polyhedral terrain (or, triangulated irregular network) that given a viewpoint, makes it possible to select the appropriate level of detail for each part of the terrain in such a way that the parts still fit together. The main advantage of our structure is that it uses the Delaunay triangulation at each level, so that triangles with very small angles are avoided. This is the first method that uses the Delaunay triangulation and still allows one to combine different levels into a single representation. (C) 1998 Academic Press.

关键词： computational geometry hierarchical data structure multiresolution modeling terrain Delaunay triangulation

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Right-triangulated irregular networks

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ALGORITHMICA 2001年第2期30卷 264-286页

作者： Evans, W Kirkpatrick, D Townsend, G Univ Arizona Dept Comp Sci Tucson AZ 85721 USA Univ British Columbia Dept Comp Sci Vancouver BC V6T 1Z4 Canada

We describe a hierarchical data structure for representing a digital terrain (height field) which contains approximations of the terrain at different levels of detail. The approximations are based on triangulations of the underlying two-dimensional space using right-angled triangles. The methods we discuss permit a single approximation to have a varying level of approximation accuracy across the surface. Thus, for example, the area close to an observer may be represented with greater detail than areas which lie outside their field of view. We discuss the application of this hierarchical data structure to the problem of interactive terrain visualization. We point out some of the advantages of this method in terms of memory usage and speed.

关键词： surface approximation digital elevation model hierarchical data structure

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Multi-scale high-performance fluid flow: Simulations through porous media

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ADVANCES IN ENGINEERING SOFTWARE 2017年 103卷 85-98页

作者： Perovic, Nevena Frisch, Jerome Salama, Amgad Sun, Shuyu Rank, Ernst Mundani, Ralf-Peter Tech Univ Munich Arcisstr 21 D-80333 Munich Germany Rhein Westfal TH Aachen Mathieustr 30 D-52074 Aachen Germany King Abdullah Univ Sci & Technol Thuwal Saudi Arabia

Computational fluid dynamic (CFD) calculations on geometrically complex domains such as porous media require high geometric discretisation for accurately capturing the tested physical phenomena. Moreover, when considering a large area and analysing local effects, it is necessary to deploy a multi-scale approach that is both memory-intensive and time-consuming. Hence, this type of analysis must be conducted on a high-performance parallel computing infrastructure. In this paper, the coupling of two different scales based on the Navier-Stokes equations and Darcy's law is described followed by the generation of complex geometries, and their discretisation and numerical treatment. Subsequently, the necessary parallelisation techniques and a rather specific tool, which is capable of retrieving data from the supercomputing servers and visualising them during the computation runtime (i.e. in situ) are described. All advantages and possible drawbacks of this approach, together with the preliminary results and sensitivity analyses are discussed in detail. (C) 2016 Elsevier Ltd. All rights reserved.

关键词： High-performance computing Porous media Interactive data exploration Multi-grid-like solver Parallel computing Multi-scale approach hierarchical data structure

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Developing a goodness of fit test for a joint model of clustered survival and count data

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COMMUNICATIONS IN STATISTICS-SIMULATION AND COMPUTATION 2022年第12期51卷 7151-7168页

作者： Adhikari, A. P. N. G. Sooriyarachchi, M. R. Univ Colombo Dept Stat Colombo 3 Sri Lanka

Mixed responses within clusters are becoming an increasingly popular phenomenon. However, this scenario is a complex one. This research is based on survival and count response data which occur frequently in medical studies. In the literature, there is no satisfactory goodness of fit test for a joint model of these two responses within a cluster setting. Therefore, the main objective of this study is to develop a GOF test for this scenario. Simulation studies were used to examine the type I error rate and the power of the test. An example was used to display the practicality of the test.

关键词： Count hierarchical data structure Joint model Mixed responses Simulation Survival

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