Ouroboros: Single-step Diffusion Models for Cycle-consistent Forward and Inverse Rendering

Shanlin Sun*1, Yifan Wang*2, Hanwen Zhang*3, Yifeng Xiong1, Qin Ren2
Ruogu Fang†4, Xiaohui Xie†1, Chenyu You†2
1University of California, Irvine     2Stony Brook University
3Huazhong University of Science and Technology     4University of Florida
Paper Code
Teaser image.

Single-step Diffusion Models for Forward and Inverse Rendering in Cycle Consistency .
Left Upper: Ouroboros decomposes input images into intrinsic maps (albedo, normal, roughness, metallicity, and irradiance). Given these generated intrinsic maps and textual prompts, our neural forward rendering model synthesizes images closely matching the originals.
Right Upper: We extend an end-to-end finetuning technique to diffusion-based neural rendering. The radar plot illustrates numerical comparisons with RGB↔X on the InteriorVerse dataset.
Bottom: Our method achieves temporally consistent video inverse rendering without specific finetuning on video data.


Abstract

While multi-step diffusion models have advanced both forward and inverse rendering, existing approaches often treat these problems independently, leading to cycle inconsistency and slow inference speed. In this work, we present Ouroboros, a framework composed of two single-step diffusion models that handle forward and inverse rendering with mutual reinforcement. Our approach extends intrinsic decomposition to both indoor and outdoor scenes and introduces a cycle consistency mechanism that ensures coherence between forward and inverse rendering outputs. Experimental results demonstrate state-of-the-art performance across diverse scenes while achieving substantially faster inference speed compared to other diffusion-based methods. We also demonstrate that Ouroboros can transfer to video decomposition in a training-free manner, reducing temporal inconsistency in video sequences while maintaining high-quality per-frame inverse rendering.


Forward Rendering

Forward rendering example - Scene 1
Forward rendering example - Scene 2
Forward rendering example - Scene 3
Method RGB Albedo Normal Roughness Metallicity Irradiance Reconstruction
Ours
Ours RGB frame Ours Albedo Ours Normal Ours Roughness Ours Metallicity Ours Irradiance Ours Reconstruction
RGB↔X
RGB↔X RGB frame RGB↔X Albedo RGB↔X Normal RGB↔X Roughness RGB↔X Metallicity RGB↔X Irradiance RGB↔X Reconstruction

Inverse Rendering

RGB Albedo Normal Roughness Metallicity Irradiance
Inverse rendering example test2 - RGB
Inverse rendering example test2 - Albedo
Inverse rendering example test2 - Normal
Inverse rendering example test2 - Roughness
Inverse rendering example test2 - Metallicity
Inverse rendering example test2 - Irradiance
Inverse rendering example test5 - RGB
Inverse rendering example test5 - Albedo
Inverse rendering example test5 - Normal
Inverse rendering example test5 - Roughness
Inverse rendering example test5 - Metallicity
Inverse rendering example test5 - Irradiance
Inverse rendering example test7 - RGB
Inverse rendering example test7 - Albedo
Inverse rendering example test7 - Normal
Inverse rendering example test7 - Roughness
Inverse rendering example test7 - Metallicity
Inverse rendering example test7 - Irradiance
Inverse rendering example MatrixCity test5 - RGB
Inverse rendering example MatrixCity test5 - Albedo
Inverse rendering example MatrixCity test5 - Normal
Inverse rendering example MatrixCity test5 - Roughness
Inverse rendering example MatrixCity test5 - Metallicity
Inverse rendering example MatrixCity test5 - Irradiance
Inverse rendering example MatrixCity test7 - RGB
Inverse rendering example MatrixCity test7 - Albedo
Inverse rendering example MatrixCity test7 - Normal
Inverse rendering example MatrixCity test7 - Roughness
Inverse rendering example MatrixCity test7 - Metallicity
Inverse rendering example MatrixCity test7 - Irradiance

BibTeX

@article{sun2025ouroboros,
  title={Ouroboros: Single-step Diffusion Models for Cycle-consistent Forward and Inverse Rendering},
  author={Sun, Shanlin and Wang, Yifan and Zhang, Hanwen and Xiong, Yifeng and Ren, Qin and Fang, Ruogu and Xie, Xiaohui and You, Chenyu},
  journal={arXiv preprint arXiv:2508.14461},
  year={2025}
}

For questions, feedback, or collaboration opportunities, please contact:
Email: shanlins@uci.edu, chenyu.you@stonybrook.edu