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

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.