Refined Identification of Urban Functional Areas Considering the Differentiated Spatial Influence of POIs—A Case Study of Changzhou

Urban functional area identification is fundamental to understanding urban spatial structure. Existing approaches typically assign a single category to each basic spatial unit, but are unable to fully represent variations in functional intensity. In this study, we introduced a refined urban functional area identification method that explicitly accounts for the heterogeneous spatial influence of points of interest (POIs) using Changzhou as a case study. The functional intensity of individual POIs was evaluated by integrating the entity scale, public recognition, and facility hierarchy, and an adaptive influence radius was constructed based on the functional intensity of individual POIs and their spatial clustering characteristics. A Gaussian distance-decay model was introduced to characterize the attenuation of the POI functional influence with increasing distance. The dominant functional areas, mixed-use functional areas, and functional transition areas were identified through functional structure analysis, function determination, and spatial aggregation. Comparison with land-use parcels showed that the method effectively identifies dominant functions. The identified functional categories, functional composition, and spatial variations in functional intensity within representative areas were highly consistent with the actual distribution of urban features. This study provides a new methodological framework for differentiated urban functional analysis and refined identification of urban functional areas.