Multi-Viewpoint Assessment of Urban Waterfront Skylines: Fractal and Spatial Hierarchy Analysis in Shanghai

With the global trend of waterfront urban expansion, nonlinear urban growth has generated skyline patterns marked by multidimensional spatial heterogeneity. Traditional single-viewpoint methods often fall short in capturing the layered spatial relationships among buildings and the complexity of multi-axis urban forms. This study focuses on the Lujiazui waterfront in Shanghai and proposes a multi-viewpoint assessment framework to evaluate urban waterfront skylines based on fractal and spatial hierarchy analysis. The framework consists of: (1) selecting eight representative viewpoints along the Huangpu River using visual cognition theory and GIS tools; (2) calculating skyline contour complexity using fractal dimension models; (3) establishing spatial hierarchy coefficients to measure depth gradients of building clusters; and (4) validating the results through visual field analysis and local skyline planning guidelines. This method integrates multi-viewpoint observation with quantitative morphological analysis, enabling a comprehensive evaluation from 2D skyline contours to 3D spatial structures. The key findings reveal that the fractal dimensions of the Lujiazui skyline demonstrate clear spatial differentiation, with viewpoints such as Financial Plaza and Chenyi Plaza reaching benchmarks typical of international metropolises. Spatial hierarchy coefficients exhibit a gradient attenuation trend, meeting the planning expectations in central zones but revealing stratification discontinuities in peripheral areas. Comparative analysis shows that over 50% of the observation points present imbalanced height ratios and excessive interface continuity, indicating potential risks associated with uncoordinated morphological control. This research confirms that multi-viewpoint assessment effectively captures spatial heterogeneity in nonlinear urban skyline development. A dual-variable evaluation model—fractal dimension and spatial hierarchy—is proposed, forming a quantitative mapping mechanism between visual characteristics and planning regulations. The findings contribute to the development of standardized 3D morphological evaluation methods for complex urban waterfront environments.