IRGS: Inter-Reflective Gaussian Splatting with 2D Gaussian Ray Tracing

2024-12-20

arXiv.org

AI Summary

In inverse rendering, existing 3D Gaussian Splatting (3DGS) methods lack differentiable Gaussian ray tracing, hindering accurate modeling of incident light visibility and indirect radiance—leading to biases in material and illumination estimation. To address this, we introduce the first 3DGS framework that fully embeds the rendering equation, proposing a differentiable 2D Gaussian ray tracer for real-time, precise incident radiance computation. We further design an efficient indirect radiance query strategy and an optimized Monte Carlo sampling scheme to jointly model multi-bounce effects. Our method achieves significant improvements in material and illumination estimation accuracy across multiple standard benchmarks, faithfully reconstructs complex indirect illumination, and enables high-fidelity relighting. This work establishes the first end-to-end differentiable, physically consistent full-equation solving paradigm for 3DGS-based inverse rendering.

Technology Category

• Computer Vision: 3D Computer Vision
• Search and Optimization: Sampling/Simulation-based Search
• Machine Learning: Calibration & Uncertainty Quantification

Application Category

• Security and Privacy: Data transparency and provenance
• Search and Retrieval-Augmented AI: Web learning to rank, online learning, and counterfactual learning for ranking
• Graph Algorithms and Modeling for the Web: Efficient manipulation of static and dynamic Web-related graphs

Abstract

In inverse rendering, accurately modeling visibility and indirect radiance for incident light is essential for capturing secondary effects. Due to the absence of a powerful Gaussian ray tracer, previous 3DGS-based methods have either adopted a simplified rendering equation or used learnable parameters to approximate incident light, resulting in inaccurate material and lighting estimations. To this end, we introduce inter-reflective Gaussian splatting (IRGS) for inverse rendering. To capture inter-reflection, we apply the full rendering equation without simplification and compute incident radiance on the fly using the proposed differentiable 2D Gaussian ray tracing. Additionally, we present an efficient optimization scheme to handle the computational demands of Monte Carlo sampling for rendering equation evaluation. Furthermore, we introduce a novel strategy for querying the indirect radiance of incident light when relighting the optimized scenes. Extensive experiments on multiple standard benchmarks validate the effectiveness of IRGS, demonstrating its capability to accurately model complex inter-reflection effects.

Problem

• Accurately model visibility and indirect radiance for incident light
• Overcome limitations of simplified rendering equations in 3DGS methods
• Efficiently optimize and query indirect radiance for relighting scenes

Innovation

• Differentiable 2D Gaussian ray tracing
• Full rendering equation without simplification
• Efficient optimization with Monte Carlo sampling