To estimate geometric accuracy, comparisons were made between the OSM data (datasets to evaluate) and BD TOPO® data (reference datasets with a metric resolution). “Homologous” objects were selected and matched manually to avoid errors related to an automated process. Differences in position were then computed on each pair of homologous objects. A specific application has been implemented in Java, based on the GeOxygene library (Bucher et al. 2010).