Directionally Factorized Illumination with Spherical Harmonic Rotation

Yimeng Dou; Adam M. Saunders; Andre T. S. Hucke; Michael E. Kim; Adam W. Anderson; Eric R. Tkaczyk; Bennett A. Landman; Daniel Moyer

arXiv · 2610.24811

Directionally Factorized Illumination with Spherical Harmonic Rotation

Yimeng Dou·Adam M. Saunders·Andre T. S. Hucke·Michael E. Kim·Adam W. Anderson·Eric R. Tkaczyk·Bennett A. Landman·Daniel Moyer

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Abstract

Many real-world capture scenarios involve an active light source rigidly attached to the camera: camera flashes for dark-environment imaging, underwater vehicle lights, and endoscopic/laparoscopic medical procedures. As the camera moves, the co-mounted light moves with it, causing the illumination direction at each surface point to change across views. Neural rendering methods (NeRF, Gaussian Splatting) encode this pose-dependent illumination as surface coloration, producing appearance inconsistencies and making it harder to recover the underlying scene. We present \textbf{DaFISH}, which can be plugged into any novel-view synthesis (NVS) pipeline such as NeRF. It factorizes per-point emitted color into surface albedo and a spherical harmonic (SH)-represented illumination factor. During training, the SH illumination is evaluated directly, enabling stable joint optimization of albedo, lighting, and geometry. \textbf{DaFISH} provides analytical generalization of illumination to arbitrary camera poses without retraining. Building on the closed-form SH-to-irradiance conversion, the training pipeline is fully differentiable from SH evaluation through volume rendering. Averaged over the held-out frames of the five scenes, \textbf{DaFISH} attains the best mean PSNR (38.91\,dB), SSIM (0.9613), and LPIPS (0.0582) among all compared methods. It improves over the strongest splatting baseline as well as the closest NeRF-based baseline, while recovering the scene consistently across views compared to prior methods.

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Yimeng Dou, Adam M. Saunders, Andre T. S. Hucke, Michael E. Kim, Adam W. Anderson, Eric R. Tkaczyk, Bennett A. Landman, Daniel Moyer. 2026-10-17. Directionally Factorized Illumination with Spherical Harmonic Rotation. https://arxiv.org/abs/2610.24811

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