UrbanGS: Efficient and Scalable Architecture for Geometrically Accurate Large-Scene Reconstruction

While 3D Gaussian Splatting (3DGS) delivers high-quality, real-time rendering for bounded scenes, its extension to large-scale urban environments introduces critical challenges in geometric consistency, memory efficiency, and computational scalability. We present UrbanGS, a scalable reconstruction framework that effectively addresses these challenges for city-scale applications. We propose a Depth-Consistent D-Normal Regularization module. In contrast to existing approaches that rely solely on monocular normal estimators—which effectively update rotation parameters but poorly optimize other geometric attributes—our method integrates D-Normal constraints with external depth supervision. This enables comprehensive updates of all geometric parameters. By further incorporating an adaptive confidence weighting mechanism based on gradient consistency and inverse depth deviation, our approach significantly enhances multi-view depth alignment and geometric coherence. To improve scalability, we introduce a Spatially Adaptive Gaussian Pruning (SAGP) strategy, which dynamically adjusts Gaussian density based on local geometric complexity and visibility to reduce redundancy. Additionally, a unified partitioning and view assignment scheme is designed to eliminate boundary artifacts and optimize computational load. Extensive experiments on multiple urban datasets demonstrate that UrbanGS achieves superior performance in rendering quality, geometric accuracy, and memory efficiency, offering a systematic solution for high-fidelity large-scale scene reconstruction.