Boundary Uncertainties in Digitized Maps: An Experiment on Digitization Errors

Abstract In this paper, an experiment is described on the study of the relationships between the digitizing error and the curvature. A simulated map was made with 8 circles of different curvatures. Ten operators digitized this map each for 6 times. An average digitizing density was determined for each operator. The original map was used as a reference for digitizing error calculation. Digitizing errors evaluated in this research included positional error, average error band, relative area error and average positional error. In addition, positional error distributions along original circle boundaries were calculated for each operator. The experiment revealed: (1)aera errors and digitizing densities tended to be larger as curvatures increases; (2) the mean distributions of positional errors caused by digitization along a circular boundary in most cases did not coincide with the boundary. The results implied that areas of small-sized compact polygons would be underestimated from digitized maps.

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