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.