Despite the advantages of polycentric structure and its rich literature drawn from cities in industialized countries, little attention has been paid to the study of polycentric urban development in developing countries based on land-use information. With Hangzhou used as a case study, the authors investigate polycentric urban development through an analysis of directions of urban expansion, urban–rural gradients, and growth types. The multidisciplinary methodology employed, based on theories and methods in remote sensing, geographic information systems, and landscape ecology, has been proved to be useful in the morphological study of polycentric urban development. It was found that Hangzhou has expanded in different directions at various speeds, shifting to a polycentric urban pattern through radial expansion. Along the main transportation corridors, the values of the mean patch sizes of urban patches displayed multiple peaks, and the landscape-shape index maintained a horizontal trend in urban fringes, reflecting the formation of polycentricity. Further, as edge growth and spontaneous growth accounted for 40%–50% and 30–40% of urban growth, respectively, and infill growth was responsible for only a small proportion of urban growth, it is suggested that dispersed urban patches have been increasingly agglomerated into big ones, especially along road corridors. Hangzhou's polycentric urban development was shaped both by the planning efforts of the government and by market forces. The municipal government guided the polycentric development through drafting and revising master plans, annexing nearby districts, and establishing development zones. Nevertheless, market forces played an increasingly important role in Hangzhou's polycentric development through the implementation of an urban land market, the inflow of migrant workers, and the relocation of industries.
Identifying urban vitality in large cities is critical for optimizing the urban fabric. While great attention has been paid to urban vitality in developed countries, related studies have been rarely conducted in developing countries. In this study, we defined urban vitality as the capacity of an urban built environment to boost lively social activities and developed a framework for measuring urban vitality using the dimensions of built environment, human activities, and human–environment interaction. Taking Shanghai, China as a case, we conducted a measurement of urban vitality using multi-source data. The results show that Shanghai follows a monocentric vital pattern within the outer ring road, with urban vitality declining from the central urban core to the city periphery. While the old urban cores tend to show high urban vitality, Pudong New Area is mostly dominated by low vitality. Three clusters with high urban vitality were identified: the old urban area, the Lujiazui CBD, and residential agglomeration areas. We conducted validation of the measuring results using phone usage density. Urban vitality showed a positive correlation with phone usage density, indicating a high accuracy of assessment. We also discovered that European-style block planning, zoning plan, mixed-functional development, urban renewal regulation, and migrant concentration were playing leading role in urban vitality of Shanghai.