NanoGS: Training-Free Gaussian Splat Simplification

TL;DR

NanoGS offers a training-free, efficient method for simplifying 3D Gaussian Splat models by merging primitives locally, significantly reducing complexity while maintaining high visual fidelity, suitable for real-time rendering.

Contribution

NanoGS introduces a novel, training-free framework for Gaussian Splat simplification using local pairwise merging based on mass-preserved moment matching.

Findings

Reduces primitive count significantly while preserving scene quality.

Operates efficiently on CPU without requiring training or GPU optimization.

Maintains compatibility with existing Gaussian Splat rendering pipelines.

Abstract

3D Gaussian Splat (3DGS) enables high-fidelity, real-time novel view synthesis by representing scenes with large sets of anisotropic primitives, but often requires millions of Splats, incurring significant storage and transmission costs. Most existing compression methods rely on GPU-intensive post-training optimization with calibrated images, limiting practical deployment. We introduce NanoGS, a training-free and lightweight framework for Gaussian Splat simplification. Instead of relying on image-based rendering supervision, NanoGS formulates simplification as local pairwise merging over a sparse spatial graph. The method approximates a pair of Gaussians with a single primitive using mass preserved moment matching and evaluates merge quality through a principled merge cost between the original mixture and its approximation. By restricting merge candidates to local neighborhoods and selecting compatible pairs efficiently, NanoGS produces compact Gaussian representations while preserving scene structure and appearance. NanoGS operates directly on existing Gaussian Splat models, runs efficiently on CPU, and preserves the standard 3DGS parameterization, enabling seamless integration with existing rendering pipelines. Experiments demonstrate that NanoGS substantially reduces primitive count while maintaining high rendering fidelity, providing an efficient and practical solution for Gaussian Splat simplification. Our project website is available at https://saliteta.github.io/NanoGS/.