# Principled BSDF¶

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.

This "Uber" shader includes multiple layers to create a wide variety of materials. The base layer is a user controlled mix between diffuse, metal, subsurface scattering and transmission. On top of that there is a specular layer, sheen layer and clearcoat layer.

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

## 入力¶

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 Color

Subsurface scattering base color.

Metallic

Blends between a non-metallic and metallic material model. A value of 1.0 gives a fully specular reflection tinted with the base color, without diffuse reflection or transmission. At 0.0 the material consists of a diffuse or transmissive base layer, with a specular reflection layer on top.

Specular

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

ヒント

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

• water: ior = 1.33, specular = 0.25

• glass: ior = 1.5, specular = 0.5

• diamond: ior = 2.417, specular = 2.15

Since materials with reflectivity above 8% do exist, the field allows values above 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

サーフェス反射とスペキュラー反射の表面のマイクロファセットラフネス(ミクロな表面の粗さ)を指定します。

ヒント

Anisotropic Cycles Only

Amount of anisotropy for specular reflection. Higher values give elongated highlights along the tangent direction; negative values give highlights shaped perpendicular to the tangent direction.

Anisotropic Rotation Cycles Only

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

ヒント

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

Clearcoat Roughness:

Roughness of clearcoat specular.

IOR

Index of refraction for transmission.

Transmission

Mix between fully opaque surface at zero and fully glass like transmission at one.

Transmission Roughness Cycles Only

With GGX distribution controls roughness used for transmitted light.

Emission (放射)

Light emission from the surface, like the Emission shader.

Emission Strength (放射の強さ)

Strength of the emitted light. A value of 1.0 will ensure that the object in the image has the exact same color as the Emission Color, i.e. make it 'shadeless'.

Alpha

Controls the transparency of the surface, with 1.0 fully opaque. Usually linked to the Alpha output of an Image Texture node.

Normal

ベース階層の法線の制御。

Clearcoat Normal

Controls the normals of the Clearcoat layer.

Tangent

Controls the tangent for the Anisotropic layer.

## Properties¶

Distribution (分布)

GGX

A method that is faster than Multiple-scattering GGX but is less physically accurate. Selecting it enables the Transmission Roughness input.

Multiple-scattering GGX

マイクロファセット間の複数のバウンス（スキャタリング）イベントを反映します。これにより、エネルギーを節約する結果が得られ、それ以外の場合は、過剰な黒ずみとして表示されます。

Subsurface Method

サブサーフェススキャタリングをシミュレートするレンダリング方法。

Christensen-Burley

Random Walk

BSDF

## 例¶

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