Assessing OSM building completeness for almost 13,000 cities globally

OpenStreetMap (OSM) is an essential source for acquiring building data, although such data may suffer from quality issues. Many studies have focused on assessing OSM building data quality but few have been carried out on a global scale. This study aims to assess OSM building completeness (a quality measure) for 12,975 cities across the globe. This was achieved by employing population grid data as a proxy for reference building data. Not only the completeness of each city but also that of the grids within that city was assessed. The assessment results were evaluated based on calculating the overall accuracy and the r-square value between estimated and reference OSM building completeness values. Results showed that for 75% of cities, the completeness is lower than 20%; no more than 9% of cities have an estimated completeness higher than 80%. The overall accuracies of most countries were higher than 80%. The estimated completeness was also highly correlated with the reference completeness, which verifies the effectiveness of our approach. These results may be useful for acquiring and updating building data in OSM. A global and open dataset related to OSM building completeness has been made available for public use.