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. Diffuse materialUsed for dull, non-reflecting materials or mesh emitters. simulates a rough surface that reflects light back into the environment in all directions. SpecularAmount of specular reflection, or the mirror-like reflection of light photons at the same angle. Used for transparent materials such as glass and water. highlights and reflections do not appear on diffuse surfaces.

Figure 1: The OctaneRender^® Diffuse material

Diffuse Material Parameters

Diffuse- Provides color to the material. This is also known as base color or albedo. You can set Diffuse color by using a value, or connecting a texture (Procedural or Image).
Roughness - Determines the spread of highlights on the surface. A high Roughness value or light color can simulate very rough surfaces such as sand paper or clay. You can set Roughness using a value, or by connecting a texture (procedural or image-based). A roughness value of 1 (white color) creates a diffuse sheen along the edges of the surface, simulating the look of crushed velvet.
Bump- Creates fine details on the material’s surface using a Procedural or Image texture. Typically a Greyscale image texture connects to this parameter - light areas of the texture give the appearance of protruding bumps, and dark areas create the appearance of indentation. You can adjust the strength of the bump map by setting the 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 on the Image texture node. These attributes are covered in more detail under the Texture category.
Normal- Creates the look of fine detail on the surface. A Normal map is a special type of image texture that uses red, green, and blue color values to perturb the normals of the surface at render time, thus 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^TM, or others to generate. To load a full color Normal map, set the Normal channel to the RGB Image data type. Note that Normal maps take precedence over Bump maps, so you cannot use a Normal map and a Bump map at the same time.
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.- Adjusts the height of the vertices of a surface at render time using a texture map. Displacement maps differ from Bump or Normal maps in that the geometry is altered by the texture, as opposed to just creating the appearance of detail. Displacement mapping is more computationally expensive than using a Bump or Normal map, but the results are more realistic, especially along the silhouette of the surface. Displacement only works with the Texture Image node, and the displaced mesh must have UV Texture coordinates. Other OctaneRender Texture nodes, such as Turbulence or Marble, will not work with Displacement. Displacement mapping is covered in more detail under the Texture Overview category.
Opacity- Determines which parts of the surface are visible in the render. Dark values indicate transparent areas, and light values indicate opaque areas. Values in between light and dark create the look of semi-transparent areas. You can lower the opacity value to fade the overall visibility of an object, or you can use a Texture map to vary the opacity across the surface. For example, if you want 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. When using an Image texture map, set the Data Type to Alpha Image if the image has an alpha channel, or Grayscale Image for black-and-white images, to load an image for setting the transparency. To invert the transparency regions, use the image's Invert checkbox.
Smooth- Smooths out the transition between surface normals. If this option is disabled, the edges between the polygons of the surface appear sharp, giving the surface a faceted look. If this option is enabled, then the edges between the polygons blend together.
Rounded Edges Radius- This parameter automatically bevels the edges of the surface at render time, without the need to alter or subdivide the geometry. Using this option enhances the realism of objects by eliminating overly sharp edges. The value refers to the radius of the rounded edge - higher values for this setting produce rounder edges.
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.
Medium- OctaneRender has three types of mediums to create translucent surfaces:
- AbsorptionDefines how fast light is absorbed while passing through a medium. Medium- Produces the appearance of a material that absorbs light while passing through a surface. The resulting color depends on the distance that light travels through the material. The Texture Overview category provides more detail about Absorption.
- ScatteringDefines how fast light gets scattered when traveling through the medium. Medium- Similar to the Absorption medium, but with an additional option for simulating subsurface scattering. Subsurface scattering is the phenomena that gives human skin and similar organic surfaces their characteristic glow under certain lighting conditions. It's a major component for creating the look of realistic skin. The Texture Overview category provides more detail about scattering.
- Volume MediumA shading system designed to render volumes such as smoke and fog. - Adds color and other qualities to a VDBDreamworks’ open-source C++ library housing the data structures and tools implementation for storing and manipulating volume data, like smoke and other amorphous materials. The purpose of OpenVDB is mostly to have an efficient way to store volumetric data in memory and on disk. It has evolved into a more general toolkit that also lets you accomplish other things, such as fracturing volumes, converting meshes to volumes and vice versa. However, it does not include a computational fluid dynamics solver, and therefore it cannot procedurally generate smoke or fire. OpenVDB is fully integrated as a library in OctaneRender. For more information about OpenVDB, please see http://www.openvdb.org/. file. VDBs are a generic volume format for creating effects such as smoke, fog, vapor, and similar gaseous objects. VDBs can consist of a single frame, or an animated sequence. 3D software packages like Houdini generate and export VDBs. You can also download VDB files at http://www.openvdb.org/download/.
Emission- Also known as a Mesh emitter, this creates a surface that emits light. To activate an emission, connect the Emission input of the Diffuse material to either a Blackbody or a Texture emission map. The Textures Overview and the Mesh Emitters categories cover maps in more detail.
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, which is only visible in areas that are in shadows. All other areas are transparent in the render.

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