Beyond the horizon: Unveiling the impact of 3D urban landscapes on residents’ perceptions through machine learning

• Moderate 3D volume and patch density maximize urban vitality. • Human-scaled bulk and extreme fragmentation regimes enhance security. • Landmark heights and low interface complexity drive aesthetic appeal. • 3D metrics far outperform 2D indices in predicting perceptions. • Functional diversity with moderate fragmentation fosters dynamic, engaging environments. With burgeoning urban populations and mounting land constraints, vertical urbanization has become indispensable for sustainable city growth. Yet the perceptual implications of three‐dimensional (3D) form remain underexplored. In this study, we combine ResNet50‐based semantic segmentation of street‐view imagery with an XGBoost regression framework interpreted via SHAP values to quantify how 3D landscape morphology shapes residents’ perceptions of vitality, security, and aesthetics. Our model achieves R2 values above 0.85 for all perceptual dimensions, substantially outperforming analogous 2D‐only approaches. We find that urban vibrancy is maximized when total 3D volume (All_3DArea) falls between 1.0 and 3.0 × 10⁶ m 3 , patch density (PD_All_3D) ranges from 5.0 × 10 −5 to 2.0 × 10 −4 , and vertical relief (RMSofHeight) remains under 10 m. Security perception peaks in human‐scaled contexts (All_3DArea < 5.0 × 10 5 ), at very low or very high fragmentation (PD_All_3D < 5.0 × 10 −5 or > 2.5 × 10 −4 ), and with moderate summit clustering (Dsummit ≈ 0.005–0.01) and gentle curvature (SummitCur < 1.0). Aesthetic appeal corresponds most strongly to landmark elevations (TenptHeight ≈ 350–400 and near 500), subtle interface complexity (S_dr < 0.05), intermediate fragmentation (PD_All_3D ≈ 1.0–1.2 × 10 −4 ), and summit density (Dsummit ≈ 0.005–0.008). By uncovering these nonlinear “sweet spots,” our findings provide precise, human‐centered guidelines for 3D urban design—informing form‐based regulations, mixed‐use zoning, and topographic modulation to foster cohesive, vibrant, and beautiful cityscapes.