顾及规则等积特性的全球离散格网建模研究

Excellent hierarchy and global seamless are the characters of Global Discrete Grid(GDG). These characters of GDG are benefit for computer data processing. In global spatial data management and multi-scale data operations, the deficiencies based on traditional planar models, such as data discontinuity, geometry distortion, topology inconsistency etc, are eliminated completely by using GDG. Now, GDG is mainly used for managing and indexing global-scale spatial data. To extend scope of GDG application in geography problem analysis, more and more GIS researchers pay attention to regularity and equal-area subdivision schemes of GDG because these characters are benefit for improving the efficiency and accuracy of global-scale spatial analysis and geo-statistical. To fulfill the requirement of global-scale spatial problem analysis, a regularity and equal-area GDG model based on "compressed octahedron" is presented in detailed. Some theories and key problems of regularity and equal-area grids subdivision scheme are approached. The detailed research topics include: subdivision scheme of regularity and equal-area GDG based on ellipsoidal surface, measurement mode and spatial relation computation rules of equal-area grid, the distribution law of equal-area grid geometry characters and evaluation accuracy criterions of global-scale spatial problem analysis by using equal-area girds. The experiment to test the feasibility and correction of methods and theories above will be done by using global multi-resolution DEM data. Regularity and equal-area gird can be considered as the basic uniform global-scale spatial frame of spatial analysis and measurement mode， and provides possible solutions for global-scale problems, such as environment monitoring, disaster emergency services, land resources geo-statistical, marine dynamic simulation and national public geographic information services etc.

全球离散格网具有离散性、层次性和全球连续性特征，既符合计算机对数据离散化处理的要求，有望从根本上解决平面模型在全球空间数据管理与多尺度操作上的数据断裂、几何变形和拓扑不一致等问题。而规则等积的离散格网能提高空间计算和统计分析的准确性和效率。因此，构建一种规则等积的全球离散格网系统已成为国际GIS学术界研究的热点之一。为此，本项目针对这一国际学术前沿和实际应用需求，以内接"压缩正八面体"为基础，对顾及规则等积性的全球离散格网建模的若干理论和关键技术进行研究，内容包括：规则等积的椭球面格网构建方法、等积格网单元的度量模式及关系计算法则、等积格网的几何特性分布规律及质量评价体系；并应用全球的多分辨率地形数据，设计和开发相应的实验。有望为大范围（或全球）的环境变化监测、灾害应急服务、国土资源统计、海洋动态模拟、国家公共地理信息服务等问题的研究，提供一个全球无缝的综合分析框架及度量模式。

针对现有全球离散格网系统无法同时兼顾等积性和层次性的缺陷，本项目首先在内接正八面体的基础上，采用四元三角剖分和九分法分别在正多面体表面建立了等积、嵌套、层次格网，分别利用等积方位投影和Snyder投影将格网投影至球面，构建出了兼顾规则性和等积的层次离散格网模型；设计了格网几何特性的评价因子（面积、角度、边长、周长和密实度），通过实验法绘制出了不同区域格网的变形情况。针对Snyder投影线非球面特征线的缺陷，利用实验分析了Snyder投影与大圆弧之间的差异，探讨了用大圆弧代替Snyder投影弧的可行性，在分析Snyder投影特点的基础上，以内接正八面体和九分法为基础，利用邻近格网的耦合性设计了一种近似规则等积的球面菱形格网系统，探讨了该格网系统的编码方案，分析了菱形格网的几何变形特征，设计了一种由球面离散格网到椭球面格网的转换方法。此外，本项目初步分析了探讨球面规则等积格网的应用模式和可视化表达方法。本项目研究为大区域乃至全球性问题（诸如海洋水体质量监测、环境问题分析模拟等）提供了一种分析框架和基础，提高了大区域空间统计分析的精度和效率。.通过项目全体人员的三年努力，项目资助发表论文７篇，其中EI检索及EI刊源（待刊）文章６篇，申请授权发明专利１项。项目组培养在读博士１名，毕业硕士４名，在读硕士４名。