基于QTM的全球离散格网变形分布及收敛分析

Distortion Distribution and Convergent Analysis of the Global Discrete Grid Based on QTM

介绍了球面四元三角网(QTM)的剖分原理;用纬线代替大圆弧线以改进QTM的传统细化方法,既减小了格网的变形量,又提高了格网数据与地理坐标的转换效率;根据实验数据,分析了在不同层次QTM格网中其面积和边长的变异性分布特征.结果表明:随着剖分层次的增加,1)格网面积的变形特征逐渐接近于正态分布;2)三角形最大/最小面积的比值和最大/最小边长的比值越来越大,但其增长速度越来越小,最终收敛到1.73和1.86.

The partition principle of QTM on sphere is introduced. In order to reduce the area or shape distortion of grids and to improve the conversion efficiency between grid data and geographic coordinates, the traditional methods of QTM partition is modified by using latitude-line instead of circle-line. Then the distortion distribution characters in areas and edges of grids are analyzed in detail based on experimental data. The result shows that with the increase of partition levels,1) distortion distribution character in areas is close to the normal distribution, and 2) the ratios of S_(max)/S_(min) and L_(max)/L_(min) become greater, but their increments are less and less, at last converging to 1.73 and 1.86 respectively.