利用最优化方法确定最佳城市独立坐标系

Utilize the Optimized Plan to Define the Best Independent Coordinate System for a City

在控制范围及相对高差较大的区域中,无论怎样选取城市独立坐标系,都会使部分区域的高斯投影变形超过2.5 cm/km。本文提出一种新的确定城市独立坐标系的最优化方法一加权蛮力搜索法,以投影变形加权平方和最小为依据,采用蛮力算法确定最优的城市独立坐标系,使得高斯投影变形超过2.5 cm/km的区域最小并集中在次要地区(权重较小的地区)。本文以吉林省延吉市独立坐标系的建立为例,研究了加权蛮力搜索法的实现途径和计算方法,并分析采用最佳城市独立坐标系后,高斯投影变形的改善情况。

After an area of large relative altitude is projected on a cylinder exterior with Gauss projection, the dis- tance between two spots in the area, however the independent coordinate system for a city is adopted, will be elon- gated or shortened by over 2.5 cm/km. A new optimized plan, for defining the best independent coordinate system for a city is proposed in this essay. By adopting brute force algorithm, the number of projected areas where the dis- tance between two spots is elongated or shortened by over 2.5 cm/km, is minimized. In the meantime, the areas are all displayed in the lesser section on the map. The establishment of independent coordinate system for Yanji, Jilin Province is taken as an example to study the approach and calculation for realizing weighted brute force algo- rithm and dissect the amelioration of the problem of distance change between two spots after Gauss projection has been conducted with new independent coordinate system defined by weighted brute force algorithm.