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Three-dimensional R tree spacial index method considering levels of detail

A multi-level of detail and spatial indexing technology, applied in the field of geographic information systems, can solve problems such as serious overlapping of nodes in the same layer, low efficiency of spatial query, irregular node shapes, etc. The effect of subtraction and node shape regularity

Inactive Publication Date: 2010-04-07
WUHAN UNIV +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0008] The purpose of the present invention is to solve the problem of low spatial query efficiency due to the phenomenon of serious overlapping of nodes on the same layer, uneven size and irregular node shape after the existing R tree index method is extended to three-dimensional space, and to provide a multi-level of detail Three-dimensional R-tree spatial indexing method

Method used

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  • Three-dimensional R tree spacial index method considering levels of detail
  • Three-dimensional R tree spacial index method considering levels of detail
  • Three-dimensional R tree spacial index method considering levels of detail

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Embodiment

[0040] The embodiment comprehensively considers the three factors of node overlap, node coverage and node shape. Through testing, it is found that the three factors are given the same weight to generate the most reasonable R-tree tree shape. Therefore, the evaluation standard is set as the comprehensive evaluation index change value Metric=Overlap / 3+Overlay / 3+Shape / 3, wherein, assuming that the side length of the node is X, Y, Z, then Overlap is the node and sibling node after the spatial object is inserted The overlap volume increase value of , Overlay is the node volume increase value after insertion, and Shape is the increase value of the node's 3D Cauchy value after insertion.

[0041] The algorithm flow of the node selection link in the embodiment is as follows. The so-called guarantee that the change value of the comprehensive evaluation index of the node is the smallest after adding the spatial object is determined by comparing the change value of the corresponding compr...

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Abstract

The invention discloses a three-dimensional R tree spacial index method considering levels of detail, which utilizes a globally optimal node selection method from bottom to top and then from top to bottom, selectively adopts a splitting mode of two into three and takes a newly-proposed three-dimensional Cauchy value as a node shape factor. The comprehensive evaluation index considering the node covering, overlapping and shape factors is enabled in the node selecting and node splitting operations, thereby ensuring the shape of the generated three-dimensional R tree to be reasonable. The management of levels of detail model is considered conveniently by means of a balanced hierarchical structure. The method supports the generation and inquiry of the spacial index of a two-dimensional and three-dimensional space target, has very high efficiencies of generation and inquiry, and can be applied to many professional fields correlative with the three-dimensional space such as various space database systems, three-dimensional roaming software and the like.

Description

technical field [0001] The invention belongs to the field of geographic information systems, and in particular relates to a three-dimensional R-tree spatial index method in consideration of multiple levels of detail. Background technique [0002] With the development of geospatial data acquisition methods such as photogrammetry, laser scanning, geological exploration and other technologies, the acquisition accuracy and modeling speed of 3D model data have been continuously improved. It reduces the complexity of the scene, and makes the amount of data surge and the types of data diverse. At the same time, in order to express the authenticity of the scene, texture data and CAD models are also widely used, and multi-level of detail has become one of the important characteristics of true 3D spatial data. The CityGML 3D city model standard, which was adopted as the OGC standard in August 2008, already has content about the integrated expression of indoor and outdoor, and the des...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G06F17/30
Inventor 朱庆龚俊张叶廷杜志强
Owner WUHAN UNIV
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