“…At present, the methods used to identify morphological characteristics of industry clusters mainly include (1) the set threshold value, based on expert opinions or experiences, (2) clustering algorithms, e.g., Local Getis-Ord Gi statistic [37], DBSCAN (density-based spatial clustering of applications with noise) [20], (3) the distance-based method, for example, Ripley's K [38], L, and M functions [39,40], and (4) methods based on density contour. Chen and Yu [41] compared the spatial distribution structure of social and economic elements in a city to the undulating terrain surface and introduced the contour tree method [22,37] into urban center recognition.…”