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Subsidence Monitoring Using Lidar and morton code Indexing

JOURNAL OF SURVEYING ENGINEERING 2016年第1期142卷 UNSP 06015002-UNSP 06015002页

作者： Ao, Jianfeng Wu, Kan Wang, YongZhi Li, Liang Jiangxi Univ Sci & Technol Sch Architectural & Surveying & Mapping Engn Ganzhou 341000 Peoples R China China Univ Min & Technol Sch Environm Sci & Spatial Informat Xuzhou 221116 Peoples R China

Point-based data-acquisition technology in traditional survey engineering does not provide complete data about mining-induced subsidence basins. To overcome these shortcomings, this research applied light detection and ranging (LIDAR) data, obtained with a terrestrial laser scanner (TLS) for monitoring the surface deformation of mining areas, to acquire full data about mining-induced subsidence basins. First, to improve the organization efficiency of LIDAR data, the decimal morton code-based indexing method was proposed for discrete-grid indexing to organize LIDAR data according to original point coordinates, to avoid the generation of grids without data, and to build a topological relationship among scattered points. Thus, this approach enabled highly efficient access of LIDAR data and restoration of coordinates for each point. In the end, the processed data were applied in engineering practice. The subsidence curves of two sections of the subsidence basin, in both strike and dip directions measured with a high-grade control survey, were compared with the subsidence curves extracted from the LIDAR data. The good coincidence effect suggests that using LIDAR data to build the subsidence basin model can result not only in richer surface-deformation information than the traditional methods but also in higher monitoring precision.

关键词： Light detection and ranging (LIDAR) points morton code Mining subsidence Terrestrial laser scanner (TLS)

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WEIGHTED ATTRIBUTE PREDICTION BASED ON morton code FOR POINT CLOUD COMPRESSION

WEIGHTED ATTRIBUTE PREDICTION BASED ON MORTON CODE FOR POINT...

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IEEE International Conference on Multimedia and Expo (ICME)

作者： Wei, Lei Wan, Shuai Sun, Zexing Ding, Xiaobin Zhang, Wei Northwestern Polytech Univ Sch Elect & Informat Xian Peoples R China Xidian Univ Sch Telecommun Engn Xian Peoples R China

ISBN: (纸本)9781728114859

The huge amount of data contained in the point cloud restrains its applications in practice. To compress the point cloud, the spatial correlation in the point cloud is explored, where adjacent points are searched and used for prediction. In this paper, an adjacent points searching method based on the morton code to find proper adjacent points is proposed, based on which a weighted prediction is performed. The proposed method locates the adjacent points quickly and accurately using the morton code of the point cloud coordinate. Experimental results show that the proposed method significantly reduces the computational complexity while maintaining similar performance as the state-of-the-art.

关键词： point cloud PCC morton code adjacent points nearest neighbors KNN

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VECTOR AND RASTER DATA STORAGE BASED ON morton code

VECTOR AND RASTER DATA STORAGE BASED ON MORTON CODE

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The ISPRS Technical Commission III Midterm Symposium on "Developments, Technologies and Applications in Remote Sensing"

作者： Guoqing Zhou Qiuyu Pan Tao Yue Qingyang Wang Hongjun Sha Shengxin Huang Xiaofan Liu Guangxi Key Laboratory of Spatial Information and Geomatics Guilin University of Technology

Even though geomatique is so developed nowadays, the integration of spatial data in vector and raster formats is still a very tricky problem in geographic information system environment. And there is still not a proper way to solve the problem. This article proposes a method to interpret vector data and raster data. In this paper, we saved the image data and building vector data of Guilin University of Technology to Oracle database. Then we use ADO interface to connect database to Visual C ++ and convert row and column numbers of raster data and X Y of vector data to morton code in Visual C++ environment. This method stores vector and raster data to Oracle Database and uses morton code instead of row and column and X Y to mark the position information of vector and raster data. Using morton code to mark geographic information enables storage of data make full use of storage space, simultaneous analysis of vector and raster data more efficient and visualization of vector and raster more intuitive. This method is very helpful for some situations that need to analyse or display vector data and raster data at the same time.

关键词： Vector and raster Integration morton code Data storage Georaster

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Parallel BVH Construction Using Locally Density Clustering

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IEEE ACCESS 2019年 7卷 105827-105839页

作者： Hu, Yingsong Wang, Weijian Li, Dan Zeng, Qingzhi Hu, Yunfei Huazhong Univ Sci & Technol Sch Comp Sci & Technol Wuhan 430074 Hubei Peoples R China

A novel bounding volume hierarchy (BVH) construction method based on locally dense clustering (LDC) was proposed for the low quality of BVH constructed in a complex scene with uneven distribution of primitives. The quality of the BVH was effectively improved by defining primitive density, analyzing the relation between density and traversal efficiency, selecting primitives with high density as the clustering center at the early stages of construction, and combining with top-down iterative clustering and bottom-up agglomerative clustering (AC). In order to effectively calculate primitive density, a local search strategy based on morton coding was adopted. This strategy can quickly get approximate primitive density information through GPU. We evaluate the method and show that, in the complex building scene with uneven distribution of primitives, our method is 13% higher in traversal speed and 11% lower in surface area heuristic (SAH) cost. That means our method can improve the rendering speed of ray tracing effectively.

关键词： Primitive density morton code local search parallel Construction

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p4est: SCALABLE ALGORITHMS FOR PARALLEL ADAPTIVE MESH REFINEMENT ON FORESTS OF OCTREES

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2011年第3期33卷 1103-1133页

作者： Burstedde, Carsten Wilcox, Lucas C. Ghattas, Omar Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA Univ Texas Austin Dept Mech Engn Jackson Sch Geosci Austin TX 78712 USA

We present scalable algorithms for parallel adaptive mesh refinement and coarsening (AMR), partitioning, and 2:1 balancing on computational domains composed of multiple connected two-dimensional quadtrees or three-dimensional octrees, referred to as a forest of octrees. By distributing the union of octants from all octrees in parallel, we combine the high scalability proven previously for adaptive single-octree algorithms with the geometric flexibility that can be achieved by arbitrarily connected hexahedral macromeshes, in which each macroelement is the root of an adapted octree. A key concept of our approach is an encoding scheme of the interoctree connectivity that permits arbitrary relative orientations between octrees. Based on this encoding we develop interoctree transformations of octants. These form the basis for high-level parallel octree algorithms, which are designed to interact with an application code such as a numerical solver for partial differential equations. We have implemented and tested these algorithms in the p4est software library. We demonstrate the parallel scalability of p4est on its own and in combination with two geophysics codes. Using p4est we generate and adapt multioctree meshes with up to 5.13 x 10(11) octants on as many as 220,320 CPU cores and execute the 2:1 balance algorithm in less than 10 seconds per million octants per process.

关键词： forest of octrees parallel adaptive mesh refinement morton code scalable algorithms large-scale scientific computing

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On the Number of Face-Connected Components of morton-Type Space-Filling Curves

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FOUNDATIONS OF COMPUTATIONAL MATHEMATICS 2019年第4期19卷 843-868页

作者： Burstedde, Carsten Holke, Johannes Isaac, Tobin INS Endenicher Allee 19b D-53115 Bonn Germany German Aerosp Ctr DLR D-51147 Cologne Germany Georgia Inst Technol Coll Comp North Ave Atlanta GA 30332 USA

Themorton-or z-curve is one example for a space-filling curve: Given a level of refinement L. N0, it maps the interval [0, 2dL) n Z one-to-one to a set of d-dimensional cubes of edge length 2-L that form a subdivision of the unit cube. Similar curves have been proposed for triangular and tetrahedral unit domains. In contrast to the Hilbert curve that is continuous, the morton-type curves produce jumps between disconnected subdomains. We prove that any contiguous subinterval of the curve divides the domain into a bounded number of face-connected subdomains. For the hypercube case in arbitrary dimension, the subdomains are star-shaped and the bound is indeed two. For the simplicial case in dimension 2, the bound is 2(L-1), and in dimension 3 it is 2L + 1, where L is the depth of refinement. We supplement the paper with theoretical and computational studies on the distribution of the number of jumps. For the hypercube curve, we can characterize the distribution by the fraction of segments of a given length that have no jump, and find that the fraction has a lower bound of 1/(2d-1) and an asymptotic upper bound of 1/2. For the simplicial curve, over 90% of all segments have three components or less.

关键词： Space-filling curve Adaptive mesh refinement morton code

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RECURSIVE ALGORITHMS FOR DISTRIBUTED FORESTS OF OCTREES

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2015年第5期37卷 C497-C531页

作者： Isaac, Tobin Burstedde, Carsten Wilcox, Lucas C. Ghattas, Omar Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA Univ Bonn Inst Numer Simulat D-53115 Bonn Germany Naval Postgrad Sch Dept Appl Math Monterrey CA 93943 USA Univ Texas Austin Dept Mech Engn Jackson Sch Geosci Austin TX 78712 USA Univ Texas Austin Inst Computat Engn & Sci Austin TX 78712 USA

The forest-of-octrees approach to parallel adaptive mesh refinement and coarsening has recently been demonstrated in the context of a number of large-scale PDE-based applications. Efficient reference software has been made freely available to the public both in the form of the standalone p4est library and more indirectly by the general-purpose finite element library deal. II, which has been equipped with a p4est backend. Although linear octrees, which store only leaf octants, have an underlying tree structure by definition, it is not fully exploited in previously published mesh-related algorithms. This is because tree branches are not explicitly stored and because the topological relationships in meshes, such as the adjacency between cells, introduce dependencies that do not respect the octree hierarchy. In this work, we combine hierarchical and topological relationships between octants to design efficient recursive algorithms that operate on distributed forests of octrees. We present three important algorithms with recursive implementations. The first is a parallel search for leaves matching any of a set of multiple search criteria, such as leaves that contain points or intersect polytopes. The second is a ghost layer construction algorithm that handles arbitrarily refined octrees that are not covered by previous algorithms, which require a 2: 1 condition between neighboring leaves. The third is a universal mesh topology iterator. This iterator visits every cell in a partition, as well as every interface (face, edge, and corner) between these cells. The iterator calculates the local topological information for every interface that it visits, taking into account the nonconforming interfaces that increase the complexity of describing the local topology. To demonstrate the utility of the topology iterator, we use it to compute the numbering and encoding of higher-order C-0 nodal basis functions used for finite elements. We analyze the complexity of the new recursive a

关键词： forest of octrees parallel adaptive mesh refinement morton code recursive algorithms large-scale scientific computing

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An out-of-core photon mapping approach to daylight coefficients

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JOURNAL OF BUILDING PERFORMANCE SIMULATION 2016年第6期9卷 620-632页

作者： Schregle, R. Grobe, L. O. Wittkopf, S. Lucerne Univ Appl Sci & Arts Competence Ctr Envelopes & Solar Energy Technikumstr 21 CH-6048 Horw Switzerland

Climate-based daylight modelling (CBDM) is an effective means of assessing the performance of daylight redirecting components (DRCs) with highly directional scattering to determine their impact on daylight availability and visual comfort. Such a simulation imposes significant computational demands on commodity hardware as it requires high density luminance samples obtained by forward raytracing. We propose an out-of-core photon mapping method within the Radiance framework to compute high quality daylight coefficients as a basis for CBDM. The method is particularly suited to angularly selective DRCs exhibiting strong redirection in conjunction with non-uniform sky luminance distributions with high resolution subdivisions. Our implementation is a work in progress and currently accommodates up to 4.3G photons on disk, while optimizing the in-core memory footprint by loading only photons which actually contribute flux to sensor points. We also leverage the fact that photon paths are independent through parallelization.

关键词： daylight simulation out-of-core paging cache photon map morton code

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A TETRAHEDRAL SPACE-FILLING CURVE FOR NONCONFORMING ADAPTIVE MESHES

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SIAM JOURNAL ON SCIENTIFIC COMPUTING 2016年第5期38卷 C471-C503页

作者： Burstedde, Carsten Holke, Johannes Rhein Friedrich Wilhelms Univ INS Bonn Germany Rhein Friedrich Wilhelms Univ HCM Bonn Germany

We introduce a space-filling curve for triangular and tetrahedral red-re finement that can be computed using bitwise interleaving operations similar to the well-known Z-order or morton curve for cubical meshes. To store sufficient information for random access, we de fine a low-memory encoding using 10 bytes per triangle and 14 bytes per tetrahedron. We present algorithms that compute the parent, children, and face-neighbors of a mesh element in constant time, as well as the next and previous element in the space-filling curve and whether a given element is on the boundary of the root simplex or not. Our presentation concludes with a scalability demonstration that creates and adapts selected meshes on a large distributed-memory system.

关键词： forest of octrees parallel adaptive mesh refinement morton code high performance computing nonconforming simplicial mesh space-filling curve

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Secret Numerical Interval Decision Protocol for Protecting Private Information and Its Application

Secret Numerical Interval Decision Protocol for Protecting P...

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Asia Conference on Algorithms, Computing and Machine Learning (CACML))

作者： Lu, Shaofeng Lv, Chengzhe Wang, Wei Xu, Changqing Fan, Huadan Lu, Yuefeng Hu, Yulong Li, Wenxi Northeastern Univ Sch Comp Sci & Engn Shenyang 110169 Peoples R China Shandong Univ Technol Sch Civil & Architectural Engn Zibo 255049 Peoples R China Guidaojiaotong Polytech Inst Foreign Cooperat & Exchange Dept Shenyang 110023 Peoples R China Chinese Acad Sci Inst Geog Sci & Nat Resources Res State Key Lab Resources & Environm Informat Syst Beijing 100101 Peoples R China China Transport Telecommun & Informat Ctr Beijing 100011 Peoples R China China Univ Geosci Sch Geog & Informat Engn Wuhan 430074 Peoples R China

ISBN: (数字)9781665482905

ISBN: (纸本)9781665482905

Cooperative secure computing based on the relationship between numerical value and numerical interval is not only the basic problems of secure multiparty computing but also the core problems of cooperative secure computing. It is of substantial theoretical and practical significance for information security in relation to scientific computing to continuously investigate and construct solutions to such problems. Based on the Goldwasser-Micali homomorphic encryption scheme, this paper propose the morton rule, according to the characteristics of the interval, a double-length vector is constructed to participate in the exclusive-or operation, and an efficient cooperative decision-making solution for integer and integer interval security is designed. This solution can solve more basic problems in cooperative security computation after suitable transformations. A theoretical analysis shows that this solution is safe and efficient. Finally, applications that are based on these protocols are presented.

关键词： privacy protection secret comparison numerical range morton code homomorphic encryption

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