Inverse rendering aims to reconstruct geometry and reflectance of objects from images. Despite recent progress, existing methods often produces inaccurate reconstructions that are sensitive to ambient illumination conditions. Here we introduce an ambient-robust inverse rendering method enabled by active RGB-NIR imaging. Our key insight is to leverage near-infrared (NIR) flash illumination-imperceptible to human observers-to obtain stable point-light shading that is largely invariant to ambient illumination. By using multi-view RGB images illuminated by ambient light and NIR images acquired with active NIR flash illumination, we reconstruct accurate geometry and reflectance by exploiting the complementary benefits of RGB and NIR images via a three-stage inverse rendering method. To enable dense multi-view acquisition, we develop an active imaging system equipped with a RGB-NIR camera and a NIR flash mounted on a mobile base. Using this system, we collect the first multi-view RGB-NIR inverse rendering dataset captured under multiple ambient illumination conditions. Experiments demonstrate that our method outperforms prior approaches, achieving accurate geometry and reflectance estimation across multiple ambient lighting scenarios.

翻译：逆渲染旨在从图像中重建物体的几何形状与反射属性。尽管近年来取得进展，现有方法常产生对环境光照条件敏感的不精确重建结果。本文提出一种基于主动RGB-NIR成像的环境鲁棒逆渲染方法。核心思路是利用人眼不可见的近红外闪光照明，获得对环境光照具有高度不变性的稳定点光源明暗信息。通过结合环境光照下的多视角RGB图像与主动NIR闪光照明下获取的NIR图像，我们采用三阶段逆渲染方法，充分利用RGB与NIR图像的互补优势，重建精确的几何与反射特性。为实现密集多视角采集，我们开发了一套主动成像系统，配备RGB-NIR相机及安装在移动基座上的NIR闪光灯。利用该系统，我们首次采集了在多种环境光照条件下拍摄的多视角RGB-NIR逆渲染数据集。实验表明，本方法优于现有技术，能在多种环境光照场景下实现精确的几何与反射估计。