FreGS: 3D Gaussian Splatting with Progressive Frequency Regularization
(2403.06908)Abstract
3D Gaussian splatting has achieved very impressive performance in real-time novel view synthesis. However, it often suffers from over-reconstruction during Gaussian densification where high-variance image regions are covered by a few large Gaussians only, leading to blur and artifacts in the rendered images. We design a progressive frequency regularization (FreGS) technique to tackle the over-reconstruction issue within the frequency space. Specifically, FreGS performs coarse-to-fine Gaussian densification by exploiting low-to-high frequency components that can be easily extracted with low-pass and high-pass filters in the Fourier space. By minimizing the discrepancy between the frequency spectrum of the rendered image and the corresponding ground truth, it achieves high-quality Gaussian densification and alleviates the over-reconstruction of Gaussian splatting effectively. Experiments over multiple widely adopted benchmarks (e.g., Mip-NeRF360, Tanks-and-Temples and Deep Blending) show that FreGS achieves superior novel view synthesis and outperforms the state-of-the-art consistently.
Overview
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FreGS introduces progressive frequency regularization to enhance 3D Gaussian Splatting, overcoming challenges of over-reconstruction.
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The framework applies a frequency annealing technique and minimizes discrepancies in spectral components, improving scene details in rendered images.
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Evaluations on multiple benchmarks show FreGS's capability in rendering high-quality images with fewer artifacts.
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FreGS advances 3D Gaussian Representation and suggests potential for broader applications in 3D computer vision tasks beyond novel view synthesis.
Enhancing 3D Gaussian Splatting with Progressive Frequency Regularization: Introduction to FreGS
Overview
The realm of 3D computer vision and novel view synthesis (NVS) has witnessed significant advancements owing to the development of Neural Radiance Fields (NeRF) and its derivatives. Notably, 3D Gaussian Splatting (3D-GS) has emerged as a promising alternative, facilitating real-time NVS with a balance between training efficiency and rendering quality. Despite its advantages, 3D-GS encounters challenges, particularly over-reconstruction, which leads to blur and artifacts in rendered images. Addressing this, we introduce the FreGS framework, which innovatively applies progressive frequency regularization (PFR) in the frequency space to refine Gaussian densification, thereby enhancing NVS performance.
Technical Foundations and Contributions
Preliminaries: The Challenge of Over-Reconstruction in 3D-GS
3D-GS, while efficient and effective in many respects, often suffers from over-reconstruction, where certain image regions get dominated by a few large Gaussians, failing to accurately represent the scene details. This results in blurred and artifact-laden rendered images. Traditionally, this issue has been somewhat challenging to address through spatial domain optimizations alone.
Progressive Frequency Regularization: A Spectral Solution
To tackle the over-reconstruction dilemma, FreGS introduces a PFR approach that operates in the frequency domain. Recognizing that both high and low spectral components play crucial roles in image representation—capturing fine details and larger structures, respectively—FreGS meticulously regularizes these components to improve Gaussian densification progressively.
- Frequency Annealing Technique: At the core of FreGS is a frequency annealing mechanism that systematically incorporates spectral components from low to high frequencies. This technique enables a more nuanced and effective Gaussian densification process, facilitating the progressive refinement of scene representations.
- Spectral Regularization Objectives: The framework minimizes discrepancies in both the amplitude and phase components between the spectral representations of rendered and ground-truth images. This dual-focus regularization ensures that both the geometric fidelity and textural nuances of the scene are well captured.
Superior Performance and Future Directions
Evaluations conducted on multiple benchmarks, including indoor and outdoor scenes from Mip-NeRF360 and Tanks-and-Temples, demonstrate FreGS's superior ability in rendering high-quality images with fewer artifacts and enhanced details. By effectively addressing the over-reconstruction issue, FreGS sets new standards in the domain of 3D GS and NVS.
Theoretical and Practical Implications
- Advancing 3D Gaussians Representation: FreGS not only advances the state of Gaussian splatting techniques by alleviating intrinsic limitations (like over-reconstruction) but also enriches the toolbox for NVS, providing a robust alternative to NeRF-based methods.
- Spectral Insights into NVS: The success of FreGS underscores the significance of frequency domain analyses in NVS tasks, suggesting that future research might further exploit spectral properties to solve analogous challenges in 3D vision.
- Applications Beyond NVS: The principles of PFR developed here could have implications beyond NVS, potentially informing the design of algorithms in related areas such as image reconstruction, denoising, and more.
Conclusion
FreGS represents a pivotal step forward in the domain of 3D computer vision, particularly in the efficient and high-quality synthesis of novel views. By pivoting to the frequency domain and employing PFR, FreGS effectively overcomes the challenges of over-reconstruction inherent in 3D-GS, paving the way for more accurate and visually appealing synthetic imagery. As we continue to explore and refine this approach, the potential for even more sophisticated and nuanced scene representations in real-time NVS seems both promising and imminent.
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