URAvatar is a novel avatar generation technology that enables the creation of realistic, re-lightable head avatars through smartphone scans under unknown lighting conditions. Unlike traditional methods that estimate reflectance parameters through inverse rendering, URAvatar directly simulates learned radiative transfer, effectively integrating global illumination into real-time rendering. This technology is significant as it can reconstruct head models that appear realistic in multiple environments from a single environmental smartphone scan, enabling real-time driving and re-lighting.