🤖 AI Summary
Existing 3D Gaussian Splatting (3DGS)-based steganographic methods struggle to simultaneously achieve high capacity, strong security, and asset usability, while remaining vulnerable to structural perturbation attacks. This work proposes a rendering-agnostic unified steganographic framework that directly embeds 3D/4D information into the native 3DGS representation. By leveraging spherical harmonic frequency importance-aware encryption, hash-grid-guided opacity mapping, and a gradient-gated consistency loss, the method constructs a continuous and attack-resilient steganographic latent manifold. It preserves visual fidelity while improving message signal-to-noise ratio by 6.28 dB and accelerating rendering speed by 3×. The approach demonstrates robustness against structural attacks such as GSPure and generalizes effectively to both 2D images and dynamic 4D scenes.
📝 Abstract
3D Gaussian Splatting (3DGS) has recently redefined the paradigm of 3D reconstruction, striking an unprecedented balance between visual fidelity and computational efficiency. As its adoption proliferates, safeguarding the copyright of explicit 3DGS assets has become paramount. However, existing invisible message embedding frameworks struggle to reconcile secure and high-capacity data embedding with intrinsic asset utility, often disrupting the native rendering pipeline or exhibiting vulnerability to structural perturbations. In this work, we present \textbf{\textit{Splats in Splats++}}, a unified and pipeline-agnostic steganography framework that seamlessly embeds high-capacity 3D/4D content directly within the native 3DGS representation. Grounded in a principled analysis of the frequency distribution of Spherical Harmonics (SH), we propose an importance-graded SH coefficient encryption scheme that achieves imperceptible embedding without compromising the original expressive power. To fundamentally resolve the geometric ambiguities that lead to message leakage, we introduce a \textbf{Hash-Grid Guided Opacity Mapping} mechanism. Coupled with a novel \textbf{Gradient-Gated Opacity Consistency Loss}, our formulation enforces a stringent spatial-attribute coupling between the original and hidden scenes, effectively projecting the discrete attribute mapping into a continuous, attack-resilient latent manifold. Extensive experiments demonstrate that our method substantially outperforms existing approaches, achieving up to \textbf{6.28 db} higher message fidelity, \textbf{3$\times$} faster rendering, and exceptional robustness against aggressive 3D-targeted structural attacks (e.g., GSPure). Furthermore, our framework exhibits remarkable versatility, generalizing seamlessly to 2D image embedding, 4D dynamic scene steganography, and diverse downstream tasks.