共查询到20条相似文献,搜索用时 140 毫秒
1.
为了实现在深度学习中能够端到端表示点云模型,提出基于八叉树和K-D树(OctKD)的点云数据表示方法。该方法将无组织的点云转换为体素空间,在体素空间对三维模型进行八叉树剖分,改进了八叉树编码方式;构建节点间的邻接关系,在GPU端并行构建八叉树;为了克服八叉树编码检索效率低的问题,采用三维K-D树索引单个三维空间点。实验结果表明该方法能够真实反映模型本身的细节特征,提高了点云模型的构造时间和检索效率。这种新的数据结构实现将点云转换为卷积神经网络可以接收的数据形式。 相似文献
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基于块段模型的三维GIS混合数据结构模型研究* 总被引:1,自引:0,他引:1
为了有效地表示三维GIS空间实体,在地质块段模型的基础上,提出了基于八叉树和四面体格网的混合数据结构模型(block octree tetrahedron,BOT模型).采用BOT模型生成算法对块段模型进行重新分割,八叉树作整体描述,四面体格网作局部精确描述,并以不同的灰度值表示不同的单元块属性.同时,为节省存储空间,提出了线性BOT编码技术.实验结果表明,BOT模型充分发挥了八叉树和四面体格网的优点,可以在不增加存储空间的前提下实现对三维目标更高效、更精确的表达. 相似文献
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Huang Y Peng J Kuo CC Gopi M 《IEEE transactions on visualization and computer graphics》2008,14(2):440-453
In this paper, we propose a generic point cloud encoder that provides a unified framework for compressing different attributes of point samples corresponding to 3D objects with arbitrary topology. In the proposed scheme, the coding process is led by an iterative octree cell subdivision of the object space. At each level of subdivision, positions of point samples are approximated by the geometry centers of all tree-front cells while normals and colors are approximated by their statistical average within each of tree-front cells. With this framework, we employ attribute-dependent encoding techniques to exploit different characteristics of various attributes. All of these have led to significant improvement in the rate-distortion (R-D) performance and a computational advantage over the state of the art. Furthermore, given sufficient levels of octree expansion, normal space partitioning and resolution of color quantization, the proposed point cloud encoder can be potentially used for lossless coding of 3D point clouds. 相似文献
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Jiang Tian Wenfei Jiang Tao Luo Kangying Cai Jingliang Peng Wencheng Wang 《The Visual computer》2012,28(6-8):819-827
In this paper, we present an adaptive-coding method for generic triangular meshes including both regular and irregular meshes. Though it is also based on iterative octree decomposition of the object space for the original mesh, as some prior arts, it has novelties in the following two aspects. First, it mathematically models the occupancy codes containing only a single–“1” bit for accurate initialization of the arithmetic coder at each octree level. Second, it adaptively prioritizes the bits in an occupancy code using a local surface smoothness measure that is based on triangle areas and therefore mitigates the effect of non-uniform vertex sampling over the surface. As a result, the proposed 3D mesh coder yields outstanding coding performance for both regular and irregular meshes and especially for the latter, as demonstrated by the experiments. 相似文献
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针对常规八叉树和线性八叉树的不足,提出了一种基于多级Z-Order曲线、无指针/无位置码的虚拟八叉树模型。在时间方面,由于采用了规则划分的节点数据块及其简单高效的索引结构,新模型具有很高的内存访问效率;在空间方面,由于节点中无指针和位置码信息,而且采用了新的基于规则节点块的合并和压缩原则,新模型具有很好的存储效率。测试结果表明,虚拟八叉树模型同时具有指针八叉树在时间效率、线性八叉树在空间效率两方面的优势,是一种高效的三维体数据组织模型,在体图形学相关的领域中具有重要的研究意义和应用价值。 相似文献
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Tang Zesheng 《计算机科学技术学报》1992,7(1):29-38
In this paper,a survey of octree representation and its applications in CAD is presented.The octree representation may be categorized as pure octree representation and polytree(or extended octree),and the latter is actually a boundary representation decomposed by octree.Linear octree which is a variant of regular octree representation has the advantage of saving memory space.The mapping between Cartesian coordinates and node addresses in linear octree is discussed.Then,algorithms for converting a boundary representation of 3D object into an octree are investiged and major approaches for transforming an octree encoded object are presented.After that,some of the applications of octree representation in CAD are listed,in particular,the applications in solid modeling,in accelerating ray tracing and in generating meshes for FEM. 相似文献
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本文提出了一种气象可视化软件原型系统(MVS)的设计与实现方案,主要介绍了MVS系统结构、模块功能、主要数据结构以及系统实现,着重阐述了提高人机交互性能而采取 的重要措施,即改进的八叉树编码方法和多进程并行处理的思想。 相似文献
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利用八元树进行物体的三维重是一种十分有效的方法。本文针对医国学图象处理中的实体三维重建顺分析了序断层图象的空间布局和八元树结构的荐,提出了一种通过断层序列图象直接建立八元树的快速算法,并易于在微机上编程实现该算法。 相似文献
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改进的八叉树数据结构 总被引:3,自引:0,他引:3
1 引言随着计算机图形学的飞速发展,三维物体的有效表示变得越来越重要,其中,八叉树表示法(octreerepresentation)以其数据结构简单、算法实现方便等特点,成为最广泛使用的三维物体的表示法之一。八叉树表示法产生于70年代末、80年代初,然而原有的八叉树数据结构存在着冗余,并且这种冗余已经存在了 相似文献
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改进的八叉树模型在3D刀轨显示系统中的应用 总被引:2,自引:0,他引:2
在传统的八叉树模型的基础上增加了扩展八叉树结点,同时引入了混合式的八叉树教据结构,并将它们应用到数控加工的三维刀轨显示系统中;叙述了实体从B-rep表示法转换为相应的改进型八叉树模型的方法,并在这种改进的八叉树模型的基础上完成对零件加工过程的实时性仿真;最后通过运行实际的数控加工程序证明该算法的可行性和有效性. 相似文献
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复杂的空间数据结构在三维GIS领域中占有突出的地位,它直接关系到GIS的功能和效率,为了有效地进行三维GIS大量数据的存储和管理,重点讨论了三维GIS栅格数据结构中的八叉树编码压缩技术,由于Morton码值的排序是实现八叉树编码压缩的基础,为此,根据Morton码排序的特殊性,提出了采用时间复杂度为O(n)的计数排序算法,使排序速度大为撇提高,在此基础上进行压缩处理,并对算法的时间及空间复杂度进行了分析,在PC机上进行的模拟实验结果表明,在目标复杂度一定的前提下,八叉树存储数据占用空间小(当分割阶次为9阶时,八叉树存储量只占栅格存储量的4.32%),是一种较为理想的描述复杂海量地理空间数据的压缩结构。 相似文献
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运用改进的八叉树算法实现精确碰撞检测 总被引:11,自引:3,他引:8
提出一种精确碰撞检测算法,通过计算空间多面体之间距离实现碰撞检测功能.在计算2个多面体之间距离时,运用空间层次划分技术高效地寻找多面体中充分接近的三角面片,然后在这些三角面片中进行距离计算,以提高算法效率;同时运用改进的八叉树层次分割算法,与基本八叉树算法相比,减少了算法的空间复杂度.文中算法已经在超导Tokamak实验装置(EAST)虚拟装配仿真系统的碰撞检测模块中得到应用,通过实验比较,证明了该算法的可行性. 相似文献
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This paper presents the design, implementation, and evaluation of the etree, a database-oriented method for large out-of-core octree mesh generation. The main idea is to map an octree to a database structure and perform all octree operations by querying and updating the database. We apply two standard database techniques, the linear octree and the B-tree, to index and store the octants on disk. Then we introduce two new techniques, auto-navigation and local balancing, to address the special needs of mesh generation. Preliminary evaluation suggests that the etree method is an effective way of generating very large octree meshes on desktop machines. 相似文献
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广义线性八元树表示及物体的广义三维重建 总被引:4,自引:0,他引:4
提出物体的广义线性八元树表示法,推广线性八元树的构造方法完成物体的广义三
维重建--广义线性八元树表示,从而为物体三维重建降低约束、增加灵活性. 相似文献
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一种改进的八元树三维目标表示方法 总被引:2,自引:0,他引:2
利用八元树表示三维物体是一种十分有效的方法。传统指针表示的八元树结构具有占据内存容量大、节点间关系少等缺点。在分析了物体的空间布局和八元树结构的基础上,文章提出了一种改进的八元树三维表示方法。从医学图像三维重建的实验结果看,提出的方法可行并且在内存存储结构和访问方式等方面优于传统的表示方法。 相似文献
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Symmetry identification of a 3-D object represented by octree 总被引:2,自引:0,他引:2
Minovic P. Ishikawa S. Kato K. 《IEEE transactions on pattern analysis and machine intelligence》1993,15(5):507-514
An algorithm for identifying symmetry of a 3-D object given by its octree is presented, and the symmetry degree (a measure of object symmetry) is proposed. The algorithm is based on traversals of the octree obtained by the principal axis transform of an input octree. An object can be in an arbitrary position and with arbitrary orientation within the octree space, and a wide range of symmetries represented by groups of proper and improper rotations can be identified. It is shown that the octree data structure supports these operations well, especially for objects whose symmetry types are simpler or equal in complexity with a fourfold rotational symmetry. The operation of the algorithm is illustrated using some synthetic test objects. The results, which are composed of identified symmetry types and the corresponding symmetry degrees, were satisfactory 相似文献