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Abstract

The appearance of a real-world feather is the result of a complex light interaction with its multi-scale biological structure including the central shaft, branching barbs and interlocking barbules on those barbs. In this work, we propose a practical surface-based appearance model for feathers. We represent the far-field appearance of feathers using a BSDF that implicitly represents the light scattering from the main biological structures of a feather such as the shaft, barb and barbules. Our model accounts for the particular characteristics of feather barbs such as the non-cylindrical cross-sections and the scattering media via a numerically-based BCSDF. To model the relative visibility between barbs and barbules, we derive a masking term for the differential projected areas of the different components of the feather’s microgeometry, which allows to analytically compute the masking between barbs and barbules. As opposed to previous works, our model uses a lightweight representation of the geometry based on a 2D texture, and does not require to explicitly represent the barbs as curves. We show the flexibility and potential of our appearance model approach to represent the most important visual features of several pennaceous feathers.

Fast Forward (SIGGRAPH 2024)

Results Gallery

An Amazon Parrot feather displays a hue and opacity variation (goniochromatic effect) caused by the visibility changes of the barbs (yellow) and barbules (green).

Ablation studies of our feather BSDF for a feather wing scene. [Only hair barbs]: Only barbs with hair BCSDF , [Only masking]: Barb and barbules with Hair BCSDF combined with our masking term similar to feather shading model from previous work, and [Full]: Adding a diffuse medulla inside the Barb BCSDF. From top to bottom materials for northern cardinal, blue-fronted amazon parrot, electus parrot and Brewer’s blackbird.

Ablation Studies Feather BSDF

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Code

Code and scenes will be released soon.

Bibtex

@article{Padron2024Feathers, author = {Padrón-Griffe, Juan Raúl and Lanza, Dario and Jarabo, Adrián and Muñoz, Adolfo}, title = {A Surface-based Appearance Model for Pennaceous Feathers}, journal = {Computer Graphics Forum}, volume = {43}, number = {7}, pages = {X}, keywords = {CCS Concepts, • Computing methodologies → Reflectance modeling}, doi = {X}, url = {X}, eprint = {X}, abstract = {The appearance of a real-world feather is the result of a complex light interaction with its multi-scale biological structure including the central shaft, branching barbs and interlocking barbules on those barbs. In this work, we propose a practical surface-based appearance model for feathers. We represent the far-field appearance of feathers using a BSDF that implicitly represents the light scattering from the main biological structures of a feather such as the shaft, barb and barbules. Our model accounts for the particular characteristics of feather barbs such as the non-cylindrical cross-sections and the scattering media via a numerically-based BCSDF. To model the relative visibility between barbs and barbules, we derive a masking term for the differential projected areas of the different components of the feather’s microgeometry, which allows to analytically compute the masking between barbs and barbules. As opposed to previous works, our model uses a lightweight representation of the geometry based on a 2D texture, and does not require to explicitly represent the barbs as curves. We show the flexibility and potential of our appearance model approach to represent the most important visual features of several pennaceous feathers.}, year = {2024} }

Acknowledgements

This project has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 956585 (PRIME). We would like to thank Diego Royo and Edurne Bernal for their help with the figures. The authors are grateful to CGTrader user rendyka for the Amazon Parrot 3D model.