CityGo: Lightweight Urban Modeling and Rendering with Proxy Buildings and Residual Gaussians
To address severe occlusion, geometric incompleteness, high memory overhead, and poor edge-deployment capability in large-scale urban aerial reconstruction, this paper proposes a hybrid representation framework combining proxy building meshes with residual 3D Gaussians. Our method innovatively integrates multi-view stereo (MVS)-derived proxy geometry with depth-guided residual Gaussians, augmented by importance-aware downsampling and joint optimization. We further incorporate zero-order spherical harmonic lighting, image reprojection constraints, and a mobile-GPU-oriented lightweight design. Evaluated on real-world aerial datasets, our approach achieves a 1.4× training speedup while significantly reducing GPU memory consumption and energy usage. Notably, it enables the first real-time rasterization-based rendering of complex urban scenes on consumer-grade mobile GPUs—overcoming fundamental limitations of 3D Gaussian splatting in dense modeling fidelity, prolonged training duration, and on-device adaptability.