Principled BSDF

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Principled BSDF.

The Principled BSDF that combines multiple layers into a single easy to use node. It is based on the Disney principled model also known as the « PBR » shader, making it compatible with other software such as Pixar’s Renderman® and Unreal Engine®. Image textures painted or baked from software like Substance Painter® may be directly linked to the corresponding parameters in this shader.

Ce shader « Uber » comprend de multiples calques pour créer une grande variètè de matériaux. Le calque de base est un mélange contrôlé par l’utilisateur entre la dispersion et la transmission diffuse, metal, subsurface. En haut de cela il y a une calque spéculaire, calque sheen et calque clearcoat.

Note

The emphasis on compatibility with other software means that it interprets certain input parameters differently from older Blender nodes.

Entrées

Base Color
Diffuse or metal surface color.
Subsurface
Mix between diffuse and subsurface scattering. Rather than being a simple mix between Diffuse and Subsurface Scattering, it acts as a multiplier for the Subsurface Radius.
Subsurface Radius
Distance de dispersion moyenne pour les canaux RVB.
Subsurface Color
Subsurface scattering base color.
Metallic
Mix between dielectric (diffuse and specular with possible transparency) and metallic (fully specular with complex Fresnel).
Specular

Amount of dielectric specular reflection. Specifies facing (along normal) reflectivity in the most common 0 - 8% range.

Indication

To compute this value for a realistic material with a known index of refraction, you may use this special case of the Fresnel formula: \(specular = ((ior - 1)/(ior + 1))^2 / 0.08\)

Par exemple :

  • eau : ior = 1.33, specular = 0.25
  • verre : ior = 1.5, specular = 0.5
  • diamant : ior = 2.417, specular = 2.15

Puisque les matériaux avec la réflectivité au dessus de 8% existent, le champ autorise des valeurs au dessus de 1.

Specular Tint

Tints the facing specular reflection using the base color, while glancing reflection remains white.

Normal dielectrics have colorless reflection, so this parameter is not technically physically correct and is provided for faking the appearance of materials with complex surface structure.

Roughness

Specifies microfacet roughness of the surface for diffuse and specular reflection.

Indication

When converting from the older Glossy BSDF node, use the square root of the original value.

Anisotropic
Quantité d’anisotropie pour la réflexion spéculaire.
Anisotropic Rotation

Rotates the direction of anisotropy, with 1.0 going full circle.

Indication

Compared to the Anisotropic BSDF node, the direction of highlight elongation is rotated by 90°. Add 0.25 to the value to correct.

Sheen
Amount of soft velvet like reflection near edges, for simulating materials such as cloth.
Sheen Tint
Mix between white and using base color for sheen reflection.
Clearcoat
Extra white specular layer on top of others. This is useful for materials like car paint and the like.
Clearcoat Roughness:
Roughness of clearcoat specular.
IOR
Index de réfraction pour la transmission.
Transmission
Mix between fully opaque surface at zero and fully glass like transmission at one.
Transmission Roughness
With GGX distribution controls roughness used for transmitted light.
Normal
Controls the normals of the base layers.
Clearcoat Normal
Contrôle les normales du calque Clearcoat.
Tangent
Contrôle la tangente pour le calque Anisotropic.

Propriétés

Distribution

Distribution Microfacet à utiliser.

GGX
Une méthode qui est plus rapide que Multiple-scattering GGX mais est moins physiquement précis. Sa sélection active l’entrée Transmission Roughness.
Multiple-scattering GGX
Prend en compte (dispersion) évènements entre microfacets. Ceci donne , autrement visible comme l’assombrissement excessif.
Subsurface Method

Rendering method to simulate subsurface scattering.

Christensen-Burley
Is an approximation to physically-based volume scattering. Gives less blurry results than Cubic and Gaussian functions.
Random Walk
Provides the most accurate results for thin and curved objects. This comes at the cost of increased render time or noise for more dense media like skin, but also better geometry detail preservation. Random Walk uses true volumetric scattering inside the mesh, which means that it works best for closed meshes. Overlapping faces and holes in the mesh can cause problems.

Sorties

BSDF
Sortie Shader standard.

Exemples

Below are some examples of how all the Principled BSDF’s parameters interact with each other.

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