Measuring positional error of circular curve features in Geographic information systems (GIS)

This paper addresses the task of modeling positional uncertainty of circular features. The specific interest provided by this study is the consideration of the actual curve function in the measurement of circular curve error. This approach differs from the existing methods based on line segment approximation. A least-squares adjustment method, composed of a series of discrete points and the covariance of these parameters, is adopted to estimate the parameters of a circular curve. Two geometric measures are developed, based on the error ellipses of the points on the circular curve: the standard deviation-based measure and the maximum distance-based measure. A comparison of the two measures for circular curves was conducted by means of a simulation experiment. The implementation of the two geometric measures is further illustrated by two case studies; one describes the positional error of digital shorelines and the other digitizes circular road curves.