Measured materials (opaque)
Measured materials (opaque)
Embedded Files
Opaque materials are defined by the way they reflect light depending on the direction of observation, and the direction and wavelength of the light arriving on the material. This behaviour can be characterized by a function called BRDF (Bidirectional Reflectance Distribution Function). The BRDF can be measured and it can be simulated in Predictive Engine.
Examples of specular measured materials
Predictive Matter supports different types of measured BRDF, identified by the tool used to measure them :
Seelab and Murakami
Seelab and Murakami
Seelab and Murakami BRDFs are stored in one single *.csv file. The file contains the measure of the material in the plane of incidence : the corresponding Input Type is "Plane".
Measured BRDFs are big sets of datas and can be heavy on the memory, the “Quality” factor given on the material for Plane and Hemispherical measures enables you to reduce the size (and quality) of a material. A quality of 1 is the original material quality. A quality of 0 is the minimum quality supported by Predictive Matter to still be able to simulate the measure.
Eldim
Eldim
Eldim BRDFs are stored in several *.dat files. Each file contains the hemispherical measure of one lobe : the measure of the material at a given incident light direction given by its azimuth and its inclination. The corresponding Input Type is "Hemisphere".
Measured BRDFs are big sets of datas and can be heavy on the memory, the “Quality” factor given on the material for Plane and Hemispherical measures enables you to reduce the size (and quality) of a material. A quality of 1 is the original material quality. A quality of 0 is the minimum quality supported by Predictive Matter to still be able to simulate the measure.
X-Rite AxF SVBRDF
X-Rite AxF SVBRDF
Predictive Engine can simulate materials stored in X-Rite material format AxF (Appearance eXchange Format). These materials are representations of measured complex materials such as textured surfaces for instance.
Examples of AxF materials
You can define an AxF material in different ways :
Use the Predictive shader or the Predictive Material edition window to link the *.axf file to the Predictive material,
If you are using the HDRP pipeline, use the Unity HDRP AxF shader,
If you have a Unity industrial license and the AxF Importer Package, use *.axf files directly as materials on your geometries. The AxF file will be automatically used in Predictive Matter as well.
You can create à Unity material automatically from a *.axf file by right-clicking on a *.axf file in the Project tab and selecting the menu "PredictiveSuite/Matter/Generate AxF Material".
You can export the content of a *.axf file (textures + log) by right-clicking on a *.axf file in the Project tab and selecting the menu "PredictiveSuite/Matter/Export AxF Datas".
Supported features :
The *.axf file stores a representation of the measured material. At the moment, Predictive Matter only supports the following representations : SVBRDF Ward (Version 1) , SVBRDF GGX (Version 1) and CarPaint2 (Version 1).
AxF materials can be represented with spectral datas. At the moment, Predictive Matter does not support spectral AxF materials with the SVBRDF Ward representation. You can still use spectral AxF materials, but their RGB representation will be used instead.
When an AxF material is defined with RGB and spectral datas, you can choose which representation is used in Predictive Matter. When using the RGB representation, the algorithm used to convert the RGB representation into a spectral representation in Predictive Matter will be either [Smits, 1999] for SVBRDF materials or the AxF internal conversion algorithm for CarPaints materials.
AxF materials can optionally include a clear coat (a thin layer of dielectric material, like polish for instance). At the moment, Predictive Matter does not support clear coats on SVBRDF AxF materials : for these materials, the clear coat will be ignored.
Predictive Matter supports the CarPaint2 representation of AxF materials but these materials must be defined using a Car Paint shader. See the Car paint section for more details.
Like all other Predictive Matter materials, AxF materials can have a normal map. In most AxF materials, normals are already included in the AxF file. If you add manually a normal map on an AxF material, the normal map contained in the AxF file will be ignored in Predictive Matter.
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