We propose progressive radiance distillation, an inverse rendering method that combines physically-based rendering with Gaussian-based radiance field rendering using a distillation progress map. Taking multi-view images as input, our method starts from a pre-trained radiance field guidance, and distills physically-based light and material parameters from the radiance field using an image-fitting process. The distillation progress map is initialized to a small value, which favors radiance field rendering. During early iterations when fitted light and material parameters are far from convergence, the radiance field fallback ensures the sanity of image loss gradients and avoids local minima that attracts under-fit states. As fitted parameters converge, the physical model gradually takes over and the distillation progress increases correspondingly. In presence of light paths unmodeled by the physical model, the distillation progress never finishes on affected pixels and the learned radiance field stays in the final rendering. With this designed tolerance for physical model limitations, we prevent unmodeled color components from leaking into light and material parameters, alleviating relighting artifacts. Meanwhile, the remaining radiance field compensates for the limitations of the physical model, guaranteeing high-quality novel views synthesis. Experimental results demonstrate that our method significantly outperforms state-of-the-art techniques quality-wise in both novel view synthesis and relighting. The idea of progressive radiance distillation is not limited to Gaussian splatting. We show that it also has positive effects for prominently specular scenes when adapted to a mesh-based inverse rendering method.

翻译：我们提出渐进式辐射蒸馏，这是一种逆向渲染方法，通过蒸馏进度图将基于物理的渲染与基于高斯泼溅的辐射场渲染相结合。以多视角图像作为输入，我们的方法从预训练的辐射场引导出发，通过图像拟合过程从辐射场中蒸馏出基于物理的光照与材质参数。蒸馏进度图初始化为较小值，这有利于辐射场渲染。在早期迭代中，当拟合的光照与材质参数尚未收敛时，辐射场回退机制确保了图像损失梯度的合理性，并避免了吸引欠拟合状态的局部极小值。随着拟合参数逐渐收敛，物理模型逐步接管渲染过程，蒸馏进度相应提升。对于物理模型未建模的光路，受影响像素上的蒸馏进度永不完成，学习到的辐射场将保留在最终渲染结果中。通过这种对物理模型局限性的容忍设计，我们防止了未建模的颜色分量渗入光照与材质参数，从而减轻重光照伪影。同时，剩余的辐射场补偿了物理模型的局限性，保证了高质量的新视角合成。实验结果表明，我们的方法在新视角合成和重光照质量方面均显著优于当前最先进技术。渐进式辐射蒸馏的思想不仅限于高斯泼溅，我们证明当将其适配于基于网格的逆向渲染方法时，对高光场景同样具有积极效果。