Diffuse Material


The DiffuseAmount of diffusion, or the reflection of light photons at different angles from an uneven or granular surface. Used for dull, non-reflecting materials or mesh emitters. material is used for dull, non-reflecting materials or light-emitting surfaces. You can edit the Diffuse materialUsed for dull, non-reflecting materials or mesh emitters. parameters when you click on the Diffuse node (figure 1).


Figure 1: The Diffuse material parameters


Diffuse Material Parameters

Diffuse - Gives color to the material. In computer graphics, this is also referred to as base color or albedo. You can set Diffuse color by using the color picker, or by connecting a Texture (Procedural or Image).

TransmissionA surface characteristic that determines if light may pass through a surface volume. - Uses a color or texture that is mixed with the material’s Diffuse color, and is most noticeable in areas affected by indirect lighting.

Roughness - Determines the spread of highlights on the surface. You can use a high Roughness value or light color to simulate very rough surfaces, such as sand paper or clay. You can set Roughness by using the color picker, or by connecting a Texture (Procedural or Image).

Medium - OctaneRender for Unreal® Engine has three types of mediums: AbsorptionDefines how fast light is absorbed while passing through a medium., ScatteringDefines how fast light gets scattered when traveling through the medium., and Volume, which you can use to create translucent surfaces. To use these options, you need to connect the Diffuse material's Medium input to the Absorption, Scattering, or Volume medium nodes.

Opacity - Determines what parts of the surface are visible in the render. Dark values indicate transparent areas, and light values determine opaque areas. Values in-between light and dark create the look of semi-transparent areas. You can lower the Opacity value to fade the object's overall visibility, or use a Texture map to vary the opacity across the surface. For example, if you wanted to make a simple polygon plane look like a leaf, you would connect a black-and-white image of the leaf’s silhouette to the Opacity channel of the Diffuse shader.

Bump - Creates fine details on the material’s surface using a Procedural or Image texture. When you connect a Greyscale texture to this parameter, the texture's light areas look like protruding bumps, and dark areas look like indentations. You can adjust the Bump map's strength by adjusting the Image texture node's Power or GammaThe function or attribute used to code or decode luminance for common displays. The computer graphics industry has set a standard gamma setting of 2.2 making it the most common default for 3D modelling and rendering applications. values. These attributes are covered in more detail under the Mediums category.

Normal - This parameter also creates fine surface details. A Normal map is a special type of Image texture that uses red, green, and blue color values to perturb the surface normals at render time, giving the appearance of added detail. They can be more accurate than Bump maps, but require specific software such as ZBrush®, Mudbox®, Substance Designer, Xnormal, or others to generate.

DisplacementThe process of utilizing a 2D texture map to generate 3D surface relief. As opposed to bump and normal mapping, Displacement mapping does not only provide the illusion of depth but it effectively displaces the actual geometric position of points over the textured surface. - The Displacement parameter adjusts the height of the surface's vertices at render time using an Image texture map. Displacement maps differs from Bump or Normal maps in that the geometry is altered by the texture, as opposed to creating the appearance of detail. Displacement mapping is more complex than using a Bump or Normal map, but the results are more realistic, in particular along the surface's silhouette. Displacement mapping is covered in more detail under the Mediums category.

Smooth - Smooths the transition between surface normals. If this option is disabled, the edges between the polygons of the surface will be sharp, giving the surface a faceted look.

Smooth Shadow Terminator - If enabled, self-intersecting shadows are smoothed according to the polygon's curvature.

Round Edges - Smooth sharp edges during render time.

Priority - Used to resolve the ambiguity in overlapping surfaces, the surface priority control allows artists to control the order of preference for surfaces. A higher number suggests a higher priority for the surface material, which means it is preferred over a lower priority surface material if a ray enters a higher priority surface and then intersects a lower priority surface while inside the higher priority surface medium.

Emission - Creates a surface that emits light (also known as a Mesh emitter). To use this option, connect the Diffuse material's Emission input to either a Blackbody or Texture emission node. These nodes are covered in more detail under the Mediums category, and in the Mesh EmittersThe ability for a surface to emit illumination usually described by a Black Body or Texture emission type. topic that's under the Lighting Overview category.

Shadow CatcherThe Shadow Catcher can be used to create shadows cast by objects onto the surrounding background imagery. The shadows cast are not limited to simply a ground plane but can be cast onto other surfaces of varying shapes. - Converts the material into a shadow catcher. When it is active, the surface is visible in the areas that are in shadow, and all other areas are transparent in the render.

Custom AOV - Writes a mask to the specified custom AOV.

Custom AOV Channel - Determines whether the custom AOV is written to a specific color channel (R, G, or B) or to all the color channels.

MaterialThe representation of the surface or volume properties of an object. Layer - Accepts any Material Layer types as an additional layer of material design.