地图数字化的坐标转换及数据的精度与相关性

Coordinate Conversion of Map Digitization,Precision and Correlation for Digitized Data

:在分析地图数字化坐标数据的误差性质时 ,通常将经过坐标转换后的坐标值作为相互独立的数字化观测值 ,而将它们与相应的已知坐标之差值当作相互独立的随机误差进行分析。为了对数字化坐标数据及其误差进行更深入严密的分析 ,本文将用来求转换参数的已知点的地面坐标和数字化坐标都视为观测值 ,并用附有参数的条件平差法来求转换参数 ,再进一步对转换后的数字化坐标的精度和其相关性进行讨论。

In studying error natures of digitized map coordinates,coordinates after conversion is usually regarded as independent digitized observations and regarded variate values between conversion coordinates and given coordinates as independent random errors.In order to analyse digitized coordinate data and those errors strictly,this paper adopted adjustment of condition equations with unknowns to solve coordinate conversion parameters,and precision and correlation for digitized coordinate errors are further discussed. Discussion showed that the former analysis method is more reasonable than others in theory and that two kinds of conversion parameters with two methods of adjustment of condition equations with unknowns and indirect adjustment are equal,but that corrected values of terrestrial coordinates and digitized coordinates regarded as observations are concerned with weight coefficients.At the same time,coordinates x i and y i of a point are not correlate after coordinate conversion,but different points are correlate. To understand this correlation further,it is suggested to study correlation,error distributions and statistical natures on the basis of taking correlation into consideration.