Chất liệu mặc định trong Blender
Principled BSDF là hệ thống material kết hợp từ nhiều lớp
- specular layer - specular layer, sheen layer and clearcoat layer
- base layer - mix between diffuse, metal, subsurface scattering and transmission
Inputs --------------------------
Base Color - Diffuse (Khuếch tán) 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 - Average distance that light scatters below the surface. Higher radius gives a softer appearance, as light bleeds into shadows and through the object. The scattering distance is specified separately for the RGB channels, to render materials such as skin where red light scatters deeper. The X, Y and Z values are mapped to the R, G and B values, respectively.
Subsurface Color - Subsurface scattering base color.
Subsurface IOR Cycles Only - Index of refraction for Subsurface Scattering.
Subsurface Anisotropy Cycles Only - Controls the directionality of subsurface scattering.
Metallic (ánh kim) - 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 (phản chiếu) - Amount of dielectric specular reflection. Specifies facing (along normal) reflectivity in the most common 0 - 8% range.
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 (độ nhám, sần sùi) - Specifies microfacet roughness of the surface for diffuse and specular reflection.
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.
Sheen (óng ánh, lấp lánh) - 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 of refraction for transmission.
Transmission (độ trong) - 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 (phát sáng) - Light emission from the surface, like the Emission shader.
Emission Strength - 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 (trong suốt) - Controls the transparency of the surface, with 1.0 fully opaque. Usually linked to the Alpha output of an Image Texture node.
Normal - Controls the normals of the base layers.
Clearcoat Normal - Controls the normals of the Clearcoat layer.
Tangent - Controls the tangent for the Anisotropic layer.
Properties --------------------------
Distribution - Microfacet distribution to use.
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 - Takes multiple bounce (scattering) events between microfacets into account. This gives a more energy conserving results, which would otherwise be visible as excessive darkening.
Subsurface Method - Rendering method to simulate subsurface scattering.
Christensen-Burley - An approximation to physically-based volume scattering. This method is less accurate than Random Walk however, in some situations this method will resolve noise faster.
Random Walk (Fixed Radius) - Provides accurate results for thin and curved objects. 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.
Random Walk - Behaves similarly to Random Walk (Fixed Radius) but modulates the Subsurface Radius based on the Color, Subsurface Anisotropy, and Subsurface IOR. This method thereby attempts to retain greater surface detail and color than Random Walk (Fixed Radius).
Outputs --------------------------
BSDF - Standard shader output.
Examples --------------------------
Below are some examples of how all the Principled BSDF’s parameters interact with each other.
../../../_images/render_shader-nodes_shader_principled_example-1a.jpg
../../../_images/render_shader-nodes_shader_principled_example-2a.jpg
../../../_images/render_shader-nodes_shader_principled_example-2b.jpg
Diffuse (Khuếch tán)
Metallic (ánh kim)
Specular (phản chiếu)
Roughness (độ thô ráp, nhám, sần sùi)
Anisotropic (vệt sáng lia ra từ tâm xoay trên mặt phay xước kim loại)
Transmission (độ trong, độ xuyên thấu) - thủy tinh
Sheen (óng ánh, lấp lánh)
Emission (phát sáng)
Refraction (khúc xạ)
Nguồn: https://docs.blender.org/manual/en/latest/render/shader_nodes/shader/principled.html
