SAGS: Structure-Aware 3D Gaussian Splatting (2404.19149v1)

Abstract: Following the advent of NeRFs, 3D Gaussian Splatting (3D-GS) has paved the way to real-time neural rendering overcoming the computational burden of volumetric methods. Following the pioneering work of 3D-GS, several methods have attempted to achieve compressible and high-fidelity performance alternatives. However, by employing a geometry-agnostic optimization scheme, these methods neglect the inherent 3D structure of the scene, thereby restricting the expressivity and the quality of the representation, resulting in various floating points and artifacts. In this work, we propose a structure-aware Gaussian Splatting method (SAGS) that implicitly encodes the geometry of the scene, which reflects to state-of-the-art rendering performance and reduced storage requirements on benchmark novel-view synthesis datasets. SAGS is founded on a local-global graph representation that facilitates the learning of complex scenes and enforces meaningful point displacements that preserve the scene's geometry. Additionally, we introduce a lightweight version of SAGS, using a simple yet effective mid-point interpolation scheme, which showcases a compact representation of the scene with up to 24$\times$ size reduction without the reliance on any compression strategies. Extensive experiments across multiple benchmark datasets demonstrate the superiority of SAGS compared to state-of-the-art 3D-GS methods under both rendering quality and model size. Besides, we demonstrate that our structure-aware method can effectively mitigate floating artifacts and irregular distortions of previous methods while obtaining precise depth maps. Project page https://eververas.github.io/SAGS/.

• The paper presents SAGS, which integrates scene geometry into 3D Gaussian splatting to improve rendering fidelity and reduce storage needs.
• It employs curvature-aware densification and a graph neural network encoder to accurately capture local structures and enrich sparse point clouds.
• The paper introduces SAGS-Lite, a lightweight model using mid-point interpolation to maintain high-quality real-time view synthesis.

Exploring Structure-Aware 3D Gaussian Splatting for Improved Neural Rendering

Introduction to 3D Gaussian Splatting

In the field of computer graphics, particularly within the domain of neural rendering and novel view synthesis, one of the more traditional approaches has been volumetric rendering, like NeRF (Neural Radiance Fields). Despite delivering impressively detailed outputs, these methods are notoriously heavy on computation, limiting their practical use in real-time applications. Enter 3D Gaussian Splatting (3D-GS), designed to sidestep some of these computational burdens by utilizing differentiable 3D Gaussians which allow for state-of-the-art rendering quality at real-time speeds on even moderately powerful GPUs.

The Issue with Conventional 3D-GS

The main pitfall of traditional 3D-GS methods lies in their structure-agnostic nature during the Gaussian optimization process. That is, each Gaussian is optimized independently, without considering the inherent geometric structure of the scene. This can lead to less accurate scene topology representation, resulting in potential artifacts and an overall drop in the quality of synthesized views.

Key limitations:

• Each Gaussian is optimized in isolation.
• Neglect of scene geometry can cause irregular distortions and affect depth accuracy, which is crucial for immersive technologies like VR/AR.

SAGS: Enhancing 3D-GS with Structure Awareness

The paper introduces Structure-Aware Gaussian Splatting (SAGS), which integrates scene geometry directly into the Gaussian optimization process. This method builds upon the foundational framework of 3D-GS but adds a layer of 'structure-awareness' that guides the optimization process, ensuring that Gaussians maintain a more accurate portrayal of the underlying scene structure.

Core Advantages:

• Enhanced Rendering Quality and Efficiency: By integrating structural knowledge into the splatting process, SAGS improves both the fidelity and efficiency of scene rendering.
• Reduction in Storage Needs: SAGS introduces a more compact representation of scenes, leading to significant reductions in storage requirements — up to 24 times smaller than traditional methods with the lightweight version, SAGS-Lite.
• Preservation of Scene Geometry: It employs local and global graph representations that help preserve spatial relationships within the scene, crucial for accurate depth measurements and VR applications.

The Technical Insights

Curvature-Aware Densification

To combat the sparse initialization problem from conventional SfM processes, SAGS applies a curvature-based densification step. This step enriches areas of the scene that are typically underrepresented in initial point clouds, leading to a more balanced and detailed point distribution for rendering.

Structure-Aware Encoder

At the heart of SAGS is its graph neural network-based encoder, which facilitates meaningful interactions and information sharing among neighboring points (or Gaussians). This approach ensures that local structures within the scene, like edges or smooth gradients, are more effectively captured and represented.

Mid-Point Interpolation (SAGS-Lite)

The paper also introduces an innovative approach within its lighter model, SAGS-Lite, which interpolates midpoints based on initial key points obtained from COLMAP, significantly reducing the model's size while maintaining rendering quality. This on-the-fly point generation is a clever trick to balance performance with computational demand.

Future Implications and Directions

The introduction and validation of SAGS open up several paths for future exploration and improvement in neural rendering. One immediate area of impact could be in augmented and virtual reality, where the demand for real-time, high-quality rendering of complex scenes is at a premium. Additionally, the success of SAGS could spur further research into how graph neural networks and other structure-preserving techniques can be leveraged in other areas of graphics and vision, like 3D reconstruction or even dynamic scene rendering.

By factoring structural knowledge into the rendering process, SAGS not only helps address some of the inefficiencies and limitations of current 3D-GS approaches but also significantly pushes the envelope on what's achievable in real-time neural rendering. As technology continues to evolve, such innovations will be pivotal in bridging the gap between high-fidelity graphics and real-time processing requirements.