Any shiny object, including plastics, glossy paint, etc., can be simulated with the OctaneRender Glossy material. The Metal material is preferred to represent physically accurate metals, however, the Glossy material in Octane can approximate metals. You can set the BRDF function to Beckmann, GGX, or Ward for reflections that are physically realistic. These models imitate actual surface characteristics including anisotropy, the fresnel effect, the rule of conservation of energy, and the physical accuracy of the specular lobes. Although not physically precise, the original Octane BRDF is helpful when it is necessary to break the restrictions.
The user interface for Glossy Material in Octane for Cinema 4D is depicted below. Following is a discussion of pertinent options:
The color of a material can be set using a value, a procedural or image-based texture, or by utilizing the Diffuse parameter, which is sometimes known as “Base Color” or “Albedo”.
The surface’s reflection is altered by this parameter. When RGB color is being used, the Float value is deactivated. Renders of different Specular values with a Roughness value of 0.0 are shown in the image below.
To mimic how smooth a surface is, the roughness parameter is used. Rougher surfaces require higher values. Although 0.0 is the default roughness value, using this value to simulate any real-world surface is unrealistic because nothing is completely smooth. For extremely smooth surfaces, low values of roughness (0.001, for instance) will result in a more realistic outcome.
In order to reflect light, specular surfaces typically produce a light lobe in the direction of the specular reflection. The difference between the light’s exit angle and specular direction determines the shape of this lobe. Due of its roughness, the resulting lobe produces a blurring effect. The blur and surface appearance increase with the size of the specular lobes. Computer jargon refers to this as “reflection blur”. In BRDFs that produce physical effects, this value behaves in accordance with the rule of conservation of energy. In other words, upon reflection, the entering light is more widely diffused, which results in energy loss. This explains why, as the lobe gets bigger, it tends to get darker. As shown below, the surface almost exhibits diffuse qualities even at extreme values. Notably, the original Octane BRDF does not adhere to this criteria; only the GGX, Ward, or Beckmann BRDF types do.
Reflections with anisotropy might be noncircular or skewed in a specific direction. Anisotropic surfaces include polished metal, fur, wood, and human hair. Only the GGX, Ward, and Beckmann BRDF models are compatible with the anisotropy feature, and a roughness value greater than 0.0 is necessary. The outcome depends on the following two values:
- Anisotropy: Controls how much anisotropy is applied to the surface. Both a negative and positive value are possible for this.
- Rotation: With this setting, the anisotropy can be specified by a procedural or grayscale picture texture (including OSL textures).
Effective surface normals and UV coordinates have a big impact on the anisotropy result. The anisotropic characteristics of various BRDF models are displayed in the following image. This image’s roughness value is fixed, and the rotation is done using a grayscale image texture.
This option is mostly used to simulate clothing and textiles that resemble velvet or satin. It functions by boosting reflectance for grazing angles with different levels of roughness. Higher roughness results in a less sharp peak and a more dispersed sheen reflection across the fabric surface, whereas lower roughness produces a stronger peak of sheen reflection around the grazing angle.
Sheen only accepts the use of GGX, Ward, or Beckmann BRDF models.
Create a Glossy material and start by entering the parameters shown in the image below to use Sheen. To alter the Sheen effect, change the Roughness setting. Sheen can also be used more effectively in combination with a composite or mix material.
The appearance of a thin film of material on the surface is simulated by film width. This will produce a prismatic appearance that resembles the colors found on a soap bubble or an oil slick’s surface. The effect is stronger when the values are larger. Use the Film Index option to modify the colors that are visible in the thin film by adjusting its Index of Refraction. Both image/procedural texture values and RGB color/Float Value values can be used with this option. The film width in the image below is represented by a grayscale image texture. 2.2 is the film index.
This quantity, also referred to as IOR or Refractive Index, establishes the surface’s ability to reflect light in accordance with the Fresnel reflection law. According to Fresnel, surface IOR values and the observer’s angle determine how much reflection occurs. Every surface actually has a refractive index. IOR values can be found at https://refractiveindex.info/. — The primary drop-down menu’s “Selected data for 3D artist” area is a nice place to start. The “n” and “k” values, also referred to as “complex index of refraction” components, are the values that are displayed at RefractiveIndex. Choose the n value for the chosen IOR because the Glossy Material lacks a slot for specifying the n and k values separately. Both the Metal and Universal materials offer slots for the n and k values if greater accuracy is needed.
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Source: Source: docs.otoy.com