四参数模型的地形图坐标系转换中同名点的筛选方法

Method of Selecting Common Points in Topographic Map Coordinate System Transformation Based on 4-Parameter Model

在测绘过程中,往往会遇到已有地形图资料的坐标系与新测地形图坐标系不一致的情况,需要将不同坐标系的地形图进行转换.小区域的地形图一般是通过选取同名点计算四参数来进行转换,选出的同名点精度直接决定了转换成果的精度.本研究提出了一种同名点筛选的方法,将同名点分解成距离分析和旋转角度分析两部份,分别采用数学统计方法进行检验,可以筛选出高精度的同名点.同时,用四川某县地形图转换中选取的同名点对该方法进行验证,得出该方法确实可以有效地筛选出高精度的同名点,从而提高地形图转换的精度.

In surveying and mapping production,the researchers often encounter the situation that the coordinate system of the existing topographic map data is inconsistent with the coordinate system of the new topographic map,so they need to transform the topographic map of different coordinate systems.In small-area topographic map,the homonymous point is generally selected to calculate the four parameters for conversion.At this time,the accuracy of the selected homonymous point directly determines the accuracy of the conversion results.In this paper,a method of selecting homonymous points is proposed.The homonymous points are divided into two parts:distance analysis and rotation angle analysis.The highprecision homonymous points can be screened by mathematical statistics.The homonymous points selected in the topographic map transformation of a county in Sichuan Province are used the method mentioned above to verify.It is concluded that this method can effectively screen out the homonymous points with high accuracy,which helps improve the accuracy of topographic map transformation.