asStandardSurface¶
A physically based material with a dielectric coating with absorption, and a substrate with optional subsurface scattering, refraction, volumetric absorption.
Parameters¶
Diffuse Parameters¶
- Diffuse Weight
- A scaling factor for the diffuse BRDF.
- Diffuse Color
- The surface color.
- Diffuse Roughness
- The diffuse roughness, with a value of 0, it corresponds to a Lambert diffuse term. Higher values flatten the appearance of the surface, giving it a chalky look. [1]
Subsurface Parameters¶
- Subsurface Weight
- A weighting factor for the subsurface scattering term.
- Subsurface Mean Free Path (MFP)
- Color controling how far light enters and travels within the medium.
- Subsurface MFP Scale
- Overall scaling factor for the MFP color, which is expected in [0,1] range. Values above 1.0 are possible, resulting in increased translucency appearance.
Advanced¶
- Subsurface Profile
The diffusion profiles to use in the BSSDRF [2]. This parameter can take the following values:
- Gaussian [dEon:2007:ERH:2383847.2383869]
- Better Dipole
- Normalized Diffusion [Christensen:2015:ARP:2775280.2792555]
- Random Walk [Meng:2016:IDS:3071773.3071778]
Translucency Parameters¶
- Translucency Weight
- Controls the amount of thin translucency of the object.
- Translucency Color
- Color affecting the thin translucency term.
Specular Parameters¶
- Specular Color
- Overall specular tint for the specular BRDF.
- Specular Roughness
- The apparent surface roughness affecting the specular highlights.
Fresnel¶
- Fresnel Type
Allows the user to choose the specular mode, of a dielectric such as plastic or glass, or of a conductor or metal.
Note
To use refraction, the mode must be set to dielectric and the index of refraction set. When in conductor mode, the face tint and edge tint parameters are used to derive the complex index of refraction instead [Gulbrandsen2014Fresnel] and no refraction is used.
- IOR
- The index of refraction for the dielectric mode.
- Facing Tint
- The reflectance at normal incidence.
- Edge Tint
- Reflectance at grazing incidence.
Anisotropy¶
- Anisotropy Amount
- Overall intensity of the anisotropy effect, with a value of 0.0 representing a isotropic specular highlight.
- Anisotropy Angle
- Rotation angle for the anisotropic highlight in [0,1], mapping a rotation from 0 to 360 degrees.
- Anisotropy Map
- Also known as tangent field, encodes the anisotropy directions along X and Y in the Red and Green or Red and Blue channels of the image. Appleseed expects values encoded in the Red and Green channels.
Refraction Parameters¶
- Refraction Amount
- Intensity of the refraction, only taking place when Fresnel is dielectric [Walter2007].
- Refraction Tint
- Overall tinting factor, it affects the BTDF equally, unlike volumetric absorption.
Volumetric Absorption¶
- Absorption Depth
- Sets the depth at which full absorption takes place. Low values result in dense absorbing materials, high values in transparent appearance ones.
- Absorption Color
- The color used for the volumetric absorption.
Coating Parameters¶
- Coating Reflectivity
- Intensity of specular highlights on the coating.
- Coating Roughness
- Apparent surface roughness of the coating specular highlights.
- Coating IOR
- Index of refraction of the coating layer, usually a dielectric, with values around 1.5.
Coating Absorption¶
- Coating Thickness
- Thickness of the coating layer, controlling the intensity of coating absorption, with 0 being no absorption, 1 being full absorption.
- Coating Absorption
- Absorption color for the coating, white has no effect, black absorbs fully.
Incandescence Parameters¶
- Incandescence Amount
- The overall intensity of the incandescence effect.
- Incandescence Type
- Color choice for incandescence color, with constant taking as input the user-set value, and blackbody using a blackbody radiator. [3]
- Incandescence Color
- Incandescence color, ignored in blackbody mode.
- Temperature
- Temperature in Kelvin degrees, ignored in constant mode.
Options¶
- Area Normalize EDF
- Normalize by the object area, so that object deformations keep the incandescence energy. If unset, deforming the object will retain the incandescence color.
- Tonemap EDF
- Tonemaps the potentially high energy result of the blackbody radiator into the [0,1] range. Disabled by default.
Note
The tonemap EDF option has effect only when incandescence type is set to blackbody.
Transparency Parameters¶
- Transparency
- Affects the presence of an object. When transparency is binary (full opaque or full transparent, with no in-between values), appleseed alpha masks should be used instead.
Bump Parameters¶
- Coating Normal
- The bump normal for the coating layer.
- Substrate Normal
- The bump normal for the substrate.
Matte Parameters¶
- Enable Matte
- Flag toggling matte holdouts on or off.
- Matte Opacity
- Overall scaling factor for the matte, from solid black to normal.
- Matte Opacity Color
- Color for the matte.
Advanced Parameters¶
- SSS Ray Depth
- Maximum number of ray bounces for the subsurface scattering term.
- SSS Threshold
- Defines the distance light has to travel within the medium to start the subsurface scattering effect. A low enough mean free path value will have a visually negligible difference from a diffuse term. This parameter sets the threshold at which the subsurface calculations start, instead of the ordinary diffuse term.
- Maximum Ray Depth
- The maximum number of bounces a ray is allowed to travel.
Outputs¶
- Output Color
- The final result color.
- Output Transparency
- The final transparency color.
- Output Matte Opacity
- The final matte opacity. Note that OSL holdout is unsupported at the moment.
Screenshots¶
Footnotes
[1] | The diffuse BRDF used is the Oren-Nayar BRDF [Oren:1994:GLR:192161.192213] |
[2] | See also Extending the Disney BRDF to a BSDF with Integrated Subsurface Scattering for details. |
[3] | https://en.wikipedia.org/wiki/Black-body_radiation |
References
[Chr15] | Per H. Christensen. An approximate reflectance profile for efficient subsurface scattering. In ACM SIGGRAPH 2015 Talks, SIGGRAPH ‘15, 25:1–25:1. New York, NY, USA, 2015. ACM. URL: http://doi.acm.org/10.1145/2775280.2792555, doi:10.1145/2775280.2792555. |
[dEonLE07] | Eugene d’Eon, David Luebke, and Eric Enderton. Efficient rendering of human skin. In Proceedings of the 18th Eurographics Conference on Rendering Techniques, EGSR‘07, 147–157. Aire-la-Ville, Switzerland, Switzerland, 2007. Eurographics Association. URL: http://dx.doi.org/10.2312/EGWR/EGSR07/147-157, doi:10.2312/EGWR/EGSR07/147-157. |
[Gul14] | Ole Gulbrandsen. Artist friendly metallic fresnel. Journal of Computer Graphics Techniques (JCGT), 3(4):64–72, December 2014. URL: http://jcgt.org/published/0003/04/03/. |
[MHD16] | Johannes Meng, Johannes Hanika, and Carsten Dachsbacher. Improving the dwivedi sampling scheme. Comput. Graph. Forum, 35(4):37–44, jul 2016. URL: https://doi.org/10.1111/cgf.12947, doi:10.1111/cgf.12947. |
[ON94] | Michael Oren and Shree K. Nayar. Generalization of lambert’s reflectance model. In Proceedings of the 21st Annual Conference on Computer Graphics and Interactive Techniques, SIGGRAPH ‘94, 239–246. New York, NY, USA, 1994. ACM. URL: http://doi.acm.org/10.1145/192161.192213, doi:10.1145/192161.192213. |
[WMLT07] | Bruce Walter, Stephen R. Marschner, Hongsong Li, and Kenneth E. Torrance. Microfacet models for refraction through rough surfaces. In Proceedings of the 18th Eurographics Conference on Rendering Techniques, EGSR‘07, 195–206. Aire-la-Ville, Switzerland, Switzerland, 2007. Eurographics Association. URL: http://dx.doi.org/10.2312/EGWR/EGSR07/195-206, doi:10.2312/EGWR/EGSR07/195-206. |