We present D-Rex, a person-specific framework for photorealistic, relightable, expressive, and animatable full-body human avatars with free-viewpoint rendering. Existing methods for relightable full-body avatars rely on explicit 3D intrinsic decomposition with analytic reflectance models, which require accurate geometry registration and careful optimization to capture realistic light transport effects. This tight coupling of relighting with avatar modeling has hindered expressiveness: to our knowledge, no existing method demonstrates strong facial animation alongside relighting, limiting applicability in telepresence, gaming, and virtual production. We propose to decouple relighting entirely from avatar modeling by treating it as an image-space post-process: a learned translation from flat-lit, albedo-like renderings to a target HDR illumination. To this end, we leverage the strong generative prior of a pre-trained video diffusion relighting model, fine-tuned via LoRA on paired flat-lit and relit frames captured in a light stage. The flat-lit driving frames are produced by an independent expressive full-body avatar framework trained under white-light conditions, requiring no modification to support relighting, making D-Rex directly applicable to any white-light avatar system. We demonstrate that D-Rex enables view- and temporally consistent relighting while faithfully preserving expressive motion and fine-grained facial detail, outperforming physically-based relightable avatar baselines. Project page is https://vcai.mpi-inf.mpg.de/projects/DRex/

翻译：摘要：本文提出D-Rex，一个面向特定人物的照片级真实感、可重光照、高表情表现力、可动画化且支持自由视角渲染的全人体化身框架。现有可重光照全身化身方法依赖基于解析反射模型的显式三维本征分解，这需要精确几何注册与精细优化才能捕捉真实光照传输效果。这种重光照与化身建模的紧密耦合限制了表情表达能力：据我们所知，现有方法均未能同时实现强面部动画与重光照，从而限制了其在远程临场、游戏和虚拟制作中的应用。我们提出将重光照完全从化身建模中解耦，将其视为图像空间的后处理过程：即从平面光照下的类漫反射渲染到目标高动态范围照明的学习映射。为此，我们利用预训练视频扩散重光照模型的强生成先验，通过基于低秩适配器微调配对平面光照帧与重光照帧（在光照舞台中采集）实现优化。平面光照驱动帧由独立的全人体化身框架在白光条件下生成，无需任何修改即可支持重光照，这使得D-Rex可直接适用于任意白光化身系统。实验表明，D-Rex在保持表情动作忠实还原与精细面部细节的同时，实现了视角与时间一致的重光照效果，性能超越基于物理的可重光照化身基线方法。项目主页：https://vcai.mpi-inf.mpg.de/projects/DRex/