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Growing Circles: A Region Growing Algorithm for Unstructured Grids and Non-aligned Boundaries [article]

Saeed Dabbaghchian
2018 Eurographics State of the Art Reports  
A circle is centered inside the region and starts to grow by increasing its radius. Its growth is limited either by the surrounding boundaries or by reaching its maximum radius.  ...  However, it works for unstructured grids as well as Cartesian ones. As an application of the method, it is applied to detect the boundaries of the upper airway cross-sections.  ...  maximum radius more circles  ... 
doi:10.2312/egp.20181018 fatcat:jk2wev5dcvdavhagprhyi6jm2i

Surface mesh segmentation and smooth surface extraction through region growing

Miguel Vieira, Kenji Shimada
2005 Computer Aided Geometric Design  
For each seed region, the algorithm iterates between region growing and surface fitting to maximize the number of connected vertices approximated by a single underlying surface.  ...  These regions are then contracted to create seed regions for region growing.  ...  We would like to thank Honda for the data sets used in this work.  ... 
doi:10.1016/j.cagd.2005.03.006 fatcat:zswiyljvszenhjxi245e4geehm

Slow Growing Subdivision (SGS) in Any Dimension: Towards Removing the Curse of Dimensionality

V. Pascucci
2002 Computer graphics forum (Print)  
We use a narrow averaging mask that is applied to the vertices of the mesh and/or to eventual functions defined on the mesh.  ...  Extension these techniques to the volumetric case would enable their use in a broad class of applications including solid modeling, scientific visualization and mesh generation.  ...  To be more precise we consider an axis-aligned infinite rectilinear grid (for simplicity we do not consider boundary effects).  ... 
doi:10.1111/1467-8659.t01-1-00605 fatcat:3p2ykc2ivfdzpflxhs73fm57kq

Slow Growing Subdivision (SGS) in Any Dimension: Towards Removing the Curse of Dimensionality

Valerio Pascucci
2002 Computer graphics forum (Print)  
We use a narrow averaging mask that is applied to the vertices of the mesh and/or to eventual functions defined on the mesh.  ...  Extension these techniques to the volumetric case would enable their use in a broad class of applications including solid modeling, scientific visualization and mesh generation.  ...  To be more precise we consider an axis-aligned infinite rectilinear grid (for simplicity we do not consider boundary effects).  ... 
doi:10.1111/1467-8659.00605 fatcat:wunuomyshnh5bcrffcntht2cty

Interior boundary-aligned unstructured grid generation and cell-centered versus vertex-centered CVD-MPFA performance

Shahid Manzoor, Michael G. Edwards, Ali H. Dogru, Tareq M. Al-Shaalan
2017 Computational Geosciences  
An unstructured grid generation procedure is proposed that automates control-volume and/or control point boundary alignment and yields a PEBI-mesh both with respect to primal and dual (essentially PEBI  ...  Grid generation for reservoir simulation must honor classical key constraints and be boundary aligned such that control-volume boundaries are aligned with geological features such as layers, shale barriers  ...  Acknowledgements We gratefully acknowledge Saudi Aramco for supporting this work.  ... 
doi:10.1007/s10596-017-9686-4 fatcat:gw4ojhvqgfcphaih7caqhd3fsy

An insight into the science of unstructured meshes in computer numerical simulation

Z. Abal Abas, S. Salleh, S. Ilias, A. F. N. Abdul Rahman, A. S. Shibghatullah, B. Mohd Aboobaider, S. Sidek
2014 Applied Mathematical Sciences  
Computer numerical simulation is a beneficial tool for studying various domains of knowledge. Among the steps in the whole process of numerical simulation is the generation of unstructured meshes.  ...  It also reviewed some fundamental concepts and frameworks for element generation in producing unstructured meshes, particularly the Delaunay triangulation and advancing front techniques.  ...  An insight into the science of unstructured meshes  ... 
doi:10.12988/ams.2014.49777 fatcat:il4x5kvesnbnxbp4pjfv4iyuti

Quadrilateral grid generation supported on complex internal boundaries using spectral methods [article]

Saúl E. Buitrago Boret Universidad Simón Bolívar, Caracas, Venezuela)
2017 arXiv   pre-print
The fundamental technique for generating such grids, is the deformation of an initial Cartesian grid and the subsequent alignment with the internal boundaries.  ...  Given a two-dimensional domain whose boundary is a closed polygonal line with internal boundaries defined also by polygonal lines, it is required to generate a grid consisting only of quadrilaterals with  ...  Hyman et al. (2000) in [9] presented a numerical algorithm that aligns a structured quadrilateral grid with internal alignment curves.  ... 
arXiv:1712.07007v1 fatcat:2nj5aurw55h5biyynt2szn6p5u

Mesh size functions for implicit geometries and PDE-based gradient limiting

Per-Olof Persson
2006 Engineering with Computers  
We present algorithms for automatic generation of a size function, discretized on a background grid, by using distance functions and numerical PDE solvers.  ...  We show examples of the techniques using Cartesian and unstructured background grids in 2-D and 3-D, and applications with numerical adaptation and mesh generation for images.  ...  For an unstructured background grid, where the elements are aligned with the boundaries, we simply assign values for h(x) on the boundary nodes and set the remaining nodal values to infinity.  ... 
doi:10.1007/s00366-006-0014-1 fatcat:slvtixil3nclbc4f2jiblyhj3y

Robustness and Scalability of Algebraic Multigrid

Andrew J. Cleary, Robert D. Falgout, Van Emden Henson, Jim E. Jones, Thomas A. Manteuffel, Stephen F. McCormick, Gerald N. Miranda, John W. Ruge
2000 SIAM Journal on Scientific Computing  
Algebraic multigrid (AMG) is currently undergoing a resurgence in popularity, due in part to the dramatic increase in the need to solve physical problems posed on very large, unstructured grids.  ...  Finally, we show some of the situations in which standard AMG does not work well, and indicate the current directions taken by AMG researchers to alleviate these di culties.  ...  Problem 14 This problem features a non-aligned anisotropic operator on the unit square, with Dirichlet boundary conditions at y = 0 and y = 1 and Neumann conditions on the other two sides.  ... 
doi:10.1137/s1064827598339402 fatcat:uzgc3dgkdfaghilhv5s4mzoioy

Interface preserving coarsening multigrid for elliptic problems with highly discontinuous coefficients

Wing Lok Wan
2000 Numerical Linear Algebra with Applications  
In view of these, we propose an interface preserving coarsening algorithm so that all the coarse grids are aligned with the interfaces for regular interface problems on structured grids, and that the interfaces  ...  It selects coarse grid points so that all the coarse grids are aligned with the interfaces for regular interface problems on structured grids, and so that the interfaces are resolved as much as possible  ...  ACKNOWLEDGEMENTS The author would like to thank Tony Chan for his constructive comments and suggestions throughout the development of this paper.  ... 
doi:10.1002/1099-1506(200010/12)7:7/8<727::aid-nla221>3.0.co;2-h fatcat:tbf5xouehva4dksptfd6a3hnq4

A frontal approach for internal node generation in Delaunay triangulations

J.-D. Müller, P. L. Roe, H. Deconinck
1993 International Journal for Numerical Methods in Fluids  
Our method uses a background grid to interpolate local mesh size parameters that is taken from the triangulation of the given boundary nodes.  ...  It is desirable that the mesh can be generated with minimum input from the user, ideally, just specifying the boundary geometry and, perhaps, a function to prescribe some desired mesh size.  ...  In our method, the front will take the form of a boundary between a 'nicely' triangulated region and a 'badly' triangulated region.  ... 
doi:10.1002/fld.1650170305 fatcat:pdoyy7ptwfe5jk3jtlhpon6bw4

Feature-Aligned Poly-Square Mapping of Large-Scale 2D Geometries for Semi-Structured Quad Mesh Generation

Celong Liu, Kelin Hu, Qin Chen, Xin Li
2020 Zenodo  
We develop a distributed algorithm to compute feature-aligned poly-square maps for large-scale 2D geometric regions and use it to construct low-distortion semi-structured quad meshes.  ...  The first is a feature-aware graph partitioning that considers workload balancing, minimal communication, geometric regularity, and feature-preserving.  ...  Figure 3 : 3 Boundary Normal Alignment for Poly-Square. (a) A pentagon before deformation; (b) deformation without boundary normal alignment; (c) deformation with boundary normal alignment.  ... 
doi:10.5281/zenodo.3653396 fatcat:xbczqhxl7jh3dfmn7urlstjhty

Vortex Visualization for Practical Engineering Applications

Monika Jankun-Kelly, Ming Jiang, David Thompson, Raghu Machiraju
2006 IEEE Transactions on Visualization and Computer Graphics  
In this paper, we present a feature-based vortex detection and visualization technique that is appropriate for large computational fluid dynamics data sets computed on unstructured meshes.  ...  In particular, we focus on the application of this technique to visualization of the flow over a serrated wing and the flow field around a spinning missile with dithering canards.  ...  ACKNOWLEDGEMENTS The authors would like to thank NSF (ITR/NGS-0326386) and DoD for supporting this research.  ... 
doi:10.1109/tvcg.2006.201 pmid:17080822 fatcat:ude4ah2bivhrfcme67trmumh7a

Semantic Geometric Modelling of Unstructured Indoor Point Cloud

Wenzhong Shi, Wael Ahmed, Na Li, Wenzheng Fan, Haodong Xiang, Muyang Wang
2018 ISPRS International Journal of Geo-Information  
Evaluating our approach on synthetic datasets achieved a precision of around 94% and a recall of around 97%, while for BLS datasets our approach achieved a precision of around 95% and a recall of around  ...  This method has three main steps: 3D segmentation using a new hybrid algorithm, room layout reconstruction, and wall-surface object reconstruction by using an enriched approach.  ...  This research is supported by projects: (a) Develop 3D Geodatabase Framework for Hong Kong -A Lightweight 3D Seamless Spatial Data Acquisition System (SSDAS) (ITP/053/16LP) and (b) A Preliminary Study  ... 
doi:10.3390/ijgi8010009 fatcat:h4ulsfgw2ndkvfagucn4dkr5hy

Effects of compressibility, pitch rate, and Reynolds number on unsteady incipient leading-edge boundary layer separation over a pitching airfoil

P. Ghosh Choudhuri, D. D. Knight
1996 Journal of Fluid Mechanics  
Public reporting burden for this collection of information is estimated to average 1 hour per respoinse. including the time for reviewing instructions. searching existing data sources. gathering and maintaining  ...  Directorate or information Operations and Reports. 1215 Jefferson Davis Highway. Suite 1204, Arlington, VA 22202-4302, and to the Office of Management and Budget.  ...  Computations have been performed using two separate algorithms (structured grid algorithm of Beam and Warming, and unstructured grid algorithm employing fluxdifference splitting method of Roe) for the  ... 
doi:10.1017/s0022112096001450 fatcat:tmun37m6n5hgrbgadgz65njqse
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