Confidence-Guided Multi-Scale Aggregation for Sparse-View High-Resolution 3D Gaussian Splatting

Sparse-view 3D Gaussian Splatting (3DGS) reconstructs scenes using 3D Gaussians from sparse input views. Yet, this method is prone to overfitting, which is exacerbated at higher resolutions as the expanded dimensionality amplifies floating artifacts and reconstruction ambiguities. In this paper, we present a systematic study of 3DGS under sparse-view conditions and varying input resolutions. While prior work has overlooked resolution as a key factor in sparse-view performance, we identify and quantify a trade-off: lower-resolution inputs facilitate stable global geometry reconstruction, whereas higher-resolution inputs enable finer detail recovery but introduce high-frequency artifacts and instability. Building on this insight, we further propose CAGS, a Confidence-Guided Multi-Scale Aggregation that reconstructs scenes through a coarse-to-fine hierarchical optimization process‌. Our approach employs a matching-based weighting aggregation strategy to anchor high-resolution reconstructions to stabilize structural priors and filtering noise through cross-scale consistency, and a multi-scale pseudo-view regularization to refine local details without amplifying noise. Extensive experiments on the LLFF and Mip-NeRF360 datasets demonstrate that CAGS significantly outperforms existing methods, particularly under demanding high-resolution conditions. ‌Moreover, our paradigm can be seamlessly integrated into other 3DGS-based pipelines, thereby extending the field from low-resolution reconstructions to high-fidelity outputs under real-world sparse-view constraints.