We present differentiable point-based inverse rendering, DPIR, an analysis-by-synthesis method that processes images captured under diverse illuminations to estimate shape and spatially-varying BRDF. To this end, we adopt point-based rendering, eliminating the need for multiple samplings per ray, typical of volumetric rendering, thus significantly enhancing the speed of inverse rendering. To realize this idea, we devise a hybrid point-volumetric representation for geometry and a regularized basis-BRDF representation for reflectance. The hybrid geometric representation enables fast rendering through point-based splatting while retaining the geometric details and stability inherent to SDF-based representations. The regularized basis-BRDF mitigates the ill-posedness of inverse rendering stemming from limited light-view angular samples. We also propose an efficient shadow detection method using point-based shadow map rendering. Our extensive evaluations demonstrate that DPIR outperforms prior works in terms of reconstruction accuracy, computational efficiency, and memory footprint. Furthermore, our explicit point-based representation and rendering enables intuitive geometry and reflectance editing.

翻译：我们提出可微点基逆渲染（DPIR），这是一种基于分析-合成的方法，可处理在不同光照条件下拍摄的图像，以估计几何形状和空间变化的双向反射分布函数。为此，我们采用点基渲染，消除了体积渲染中每条光线多次采样的需求，从而显著提升了逆渲染的速度。为实现这一想法，我们设计了一种混合点-体积几何表示，以及一种正则化基-双向反射分布函数反射率表示。混合几何表示通过点基溅射实现快速渲染，同时保留了基于有符号距离函数表示的几何细节与稳定性。正则化基-双向反射分布函数缓解了因光照-视角角度样本有限导致的逆渲染病态问题。我们还提出了一种基于点基阴影映射的高效阴影检测方法。大量实验表明，DPIR在重建精度、计算效率和内存占用方面均优于先前方法。此外，我们的显式点基表示与渲染支持直观的几何与反射编辑。