Evaluating the Quality of Authoritative Geospatial Datasets

Abstract

General Directorate of Surveying is considered one of the most important sources of maps in Iraq. It produced digital maps for whole Iraq in the last six years. These maps are produced from different data sources with unknown accuracy; therefore, the quality of these maps needs to be assessed. The main aim of this study is to evaluate the positional accuracy of digital maps that produced from General Directorate of Surveying. Two different study areas were selected: AL-Rusafa and AL-Karkh in Baghdad / Iraq with an area of 172.826 and 135.106 square kilometers, respectively. Different statistical analyses were conducted to calculate the elements of positional accuracy assessment (mean µ, root mean square error RMSE, minimum and maximum errors). According to the obtained results, it can be stated that the maps of the General Directorate of Surveying can be used in reconnaissance or in works that require low or specified positional accuracy (eg. ±5m), and it cannot be used for applications need high accuracy (e.g. precise surveying).