Quantifying spatial patterns of urban building morphology in the China's Guangdong-Hong Kong-Marco greater bay area

Understanding the spatial patterns of urban building morphology is crucial for revealing the interplay between the built and social environments. Previous research has predominantly concentrated on the computation of building-level metrics which makes it challenging to quantify and compare spatial patterns and variations across different cities. Using the newly available world settlement footprint 3D (WSF3D) data, this study examines the spatial patterns of urban building morphology across various cities within the Guangdong-Hong Kong-Macao Greater Bay Area, a rapidly urbanizing region in China. Specifically, we applied a concentric ring approach to delineate the spatial gradients of the building fraction, area, height, and volume from the urban center to the suburban fringes. Subsequently, we utilized dynamic time warping and a multi-dimensional scaling technique facilitating a comparative analysis of these gradients across cities. Developed cities demonstrated more homogenous distributions of building morphologies; however, notable differences were observed among the spatial patterns of distinct building metrics. Furthermore, a correlation between the spatial patterns of urban building morphology and degree of urban development was revealed, suggesting that developed cities exhibit significantly smaller declines in building morphology from the urban core to the rural periphery.