International Journal of Geo-Information Article Detecting Urban Polycentric Structure from POI Data Yue Deng 1, Jiping Liu 1,2,*, Yang Liu 3 and An Luo 2 1 School of Resource and Environmental Science, Wuhan University, 129 Luoyu Road, Wuhan 430079, China;
[email protected] 2 Research Center of Government GIS, Chinese Academy of Surveying and Mapping, Beijing 100830, China;
[email protected] 3 Beijing Institute of Applied Science and Technology, Beijing 100091, China;
[email protected] * Correspondence:
[email protected]; Tel.: +86-136-9128-0025 Received: 30 April 2019; Accepted: 15 June 2019; Published: 17 June 2019 Abstract: It is meaningful to analyze urban spatial structure by identifying urban subcenters, and many methods of doing so have been proposed in the published literature. Although these methods are widely applied, they exhibit obvious shortcomings that limit their further application. Therefore, it is of great value to propose a new urban subcenter identification method that can overcome these shortcomings. In this paper, we propose the density contour tree (DCT) method for detecting urban polycentric structures and their spatial distributions. Conceptually, this method is based on an analogy between urban spatial structure and terrain. The point-of-interest (POI) density is visualized as a continuous mathematical surface representing the urban terrain. Peaks represent the regions of the most frequent human activity, valleys represent regions with small population densities in the city, and slopes represent spatial changes in urban land-use intensity. Using this method, we have detected the urban “polycentric” structure of Beijing and determined the corresponding spatial relationships.