Learning Neural Transmittance for Efficient Rendering of Reflectance Fields

BMVC 2021

Mohammad Shafiei¹ Sai Bi^1,2 Zhengqin Li¹ Aidas Liaudanskas³ Rodrigo Ortiz-Cayon³ Ravi Ramamoorthi¹

¹University of California, San Diego ²Adobe Research ³Fyusion Inc.

Abstract

Recently neural volumetric representations such as neural reflectance fields have been widely applied to faithfully reproduce the appearance of real-world objects and scenes under novel viewpoints and lighting conditions. However, it remains challenging and time-consuming to render such representations under complex lighting such as environment maps, which requires individual ray marching towards each single light to calculate the transmittance at every sampled point. In this paper, we propose a novel method based on precomputed Neural Transmittance Functions to accelerate the rendering of neural reflectance fields. Our neural transmittance functions enable us to efficiently query the transmittance at an arbitrary point in space along an arbitrary ray without tedious ray marching, which effectively reduces the time-complexity of the rendering. We propose a novel formulation for the neural transmittance function, and train it jointly with the neural reflectance fields on images captured under collocated camera and light, while enforcing monotonicity. Results on real and synthetic scenes demonstrate almost two order of magnitude speedup for renderings under environment maps with minimal accuracy loss.

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Bibtex

        @article{shafiei2021NeuralTransmittance,
            title = {Learning Neural Transmittance for Efficient Rendering of Reflectance Fields},
            author = {Shafiei, Mohammad and Bi, Sai and
                Li, Zhengqin and Liaudanskas, Aidas and Ortiz-Cayon, Rodrigo and Ramamoorthi, Ravi},
            journal={British Machine Vision Conference (BMVC)},
            year={2021},
            }