StopThePop: Sorted Gaussian Splatting for View-Consistent Real-time Rendering (2402.00525v3)

Abstract: Gaussian Splatting has emerged as a prominent model for constructing 3D representations from images across diverse domains. However, the efficiency of the 3D Gaussian Splatting rendering pipeline relies on several simplifications. Notably, reducing Gaussian to 2D splats with a single view-space depth introduces popping and blending artifacts during view rotation. Addressing this issue requires accurate per-pixel depth computation, yet a full per-pixel sort proves excessively costly compared to a global sort operation. In this paper, we present a novel hierarchical rasterization approach that systematically resorts and culls splats with minimal processing overhead. Our software rasterizer effectively eliminates popping artifacts and view inconsistencies, as demonstrated through both quantitative and qualitative measurements. Simultaneously, our method mitigates the potential for cheating view-dependent effects with popping, ensuring a more authentic representation. Despite the elimination of cheating, our approach achieves comparable quantitative results for test images, while increasing the consistency for novel view synthesis in motion. Due to its design, our hierarchical approach is only 4% slower on average than the original Gaussian Splatting. Notably, enforcing consistency enables a reduction in the number of Gaussians by approximately half with nearly identical quality and view-consistency. Consequently, rendering performance is nearly doubled, making our approach 1.6x faster than the original Gaussian Splatting, with a 50% reduction in memory requirements.

• The paper introduces a hierarchical Gaussian splatting method that minimizes popping artifacts in real-time 3D rendering.
• The method employs tile-based culling with per-tile and per-pixel sorting to optimize depth ordering and blending.
• Results show improved view consistency, reduced memory usage, and nearly doubled rendering speed compared to traditional approaches.

Analysis of "StopThePop: Sorted Gaussian Splatting for View-Consistent Real-time Rendering"

The paper "StopThePop: Sorted Gaussian Splatting for View-Consistent Real-time Rendering" presents a novel hierarchical method to address the popping artifacts associated with Gaussian splatting techniques in real-time 3D rendering. This work builds upon the existing 3D Gaussian Splatting (3DGS) framework, with a focus on improving the rendering consistency across different viewpoints.

Problem Statement and Motivation

Gaussian splatting techniques have been prominent in rendering pipelines due to their ability to create accurate 3D representations from 2D images. However, a significant limitation of the traditional 3DGS approach is the introduction of popping artifacts during view rotations. These artifacts stem from the global sorting mechanism that, while efficient, fails to maintain consistent depth ordering as the viewpoint changes, leading to unsightly abrupt changes in the rendered scene.

Methodology

The authors introduce a hierarchical rasterization technique that dynamically adjusts the sorting and blending of Gaussian splats on a per-pixel basis. This novel method employs the computation of an optimal projection depth (t_{opt}), derived to pinpoint the location where each Gaussian contributes the most to any given ray.

Key contributions and strategies include:

1. Tile-Based Culling: Initial bounding allows for the elimination of non-contributing Gaussians, significantly reducing computational overhead.
2. Hierarchical Rasterizer: The process divides the screen into tiles, and further nests hierarchical levels within each tile. This structure supports per-pixel sorting by leveraging coherence across neighboring view rays.
3. Per-Tile and Per-Pixel Sorting: The technique fine-tunes sorting at multiple levels, minimizing the possibility of popping while maintaining performance efficiency.

Results

Empirically, the hierarchical method significantly reduces the popping artifacts that were perceptibly present in prior methods. The results indicate:

• A modest 4% performance overhead compared to the Gaussian Splatting baseline, owing to the more intricate sorting mechanism.
• An improvement in view consistency, especially notable in visual discrepancy metrics such as F, which proved to be more sensitive to popping than traditional metrics like MSE.
• A reduction in render time and memory requirements when utilizing the established pipeline, with nearly double the rendering speed and half the memory footprint compared to the original methods.

Implications

The implications of this paper are both practical and theoretical. Practically, real-time rendering applications such as virtual reality and complex simulations can leverage this framework to provide more stable and visually appealing outputs. Theoretically, this work challenges the assumptions of global sorting schemes and introduces a more granular approach to handling visual consistency in 3D scene rendering.

Future Directions

While the proposed methodology has demonstrated significant improvements, further exploration is warranted in the area of fully realizing volumetric rendering equations that consider overlap among Gaussians. Additionally, exploring how this methodology adapts to dynamic scene changes and scaled environments could expand its applicability.

Conclusion

The authors present a compelling case for a refined hierarchical approach to Gaussian splatting, effectively mitigating popping artifacts and enhancing visual fidelity in 3D rendering. This work not only advances the current understanding of Gaussian rendering pipelines but also sets a foundation for future exploration into more consistent and efficient ray-based rendering techniques. The open-source availability of their renderer further encourages continued research and application in real-time graphics and related fields.