OctaneRender® supports participating media inside objects. These settings are stored in Medium nodes, which are attached to the corresponding input pin of 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. or Specular materialUsed for transparent materials such as glass and water. nodes.
There are three types of Medium nodes:
To render with Medium nodes, the Path Tracing or PMC render kernels are the best choices. You can render mediums using the Direct Light kernel, but only if the Medium node is connected to Diffuse materialUsed for dull, non-reflecting materials or mesh emitters., and if you set the kernel's Diffuse mode to GI.
To add a Medium node to a scene, select the MaterialThe representation of the surface or volume properties of an object. and select Medium from MaterialsA set of attributes or parameters that describe surface characteristics. Tab and choose the type of node you want to use. You should connect Absorption and Scattering mediums to the Medium input of the Diffuse or 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. material. Volume mediums can connect to 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 inputs (Refer to section Effects → Volumes). Schlick Phase Function and Volume Gradient are special nodes that modify the other Medium nodes.
Note: In the plugin only Schlick Phase is available. Volume Gradient can be used in the Standalone preparing ORBXThe ORBX file format is the best way to transfer scene files from 3D Authoring software programs that use the Octane Plug-in such as Octane for Maya, Octane for Cinema 4D, or OctaneRender Standalone. This format is more efficient than FBX when working with Octane specific data as it provides a flexible, application independent format. ORBX is a container format that includes all animation data, models, textures etc. that is needed to transfer an Octane scene from one application to another. or OCs files to import in the plugin. Refer to section Effects → Volumes
Figure 1: Select the Medium node the Materials Tab.
There are some things to keep in mind about using MediumsThe behavior of light inside a surface volume described by scatter, absorption, and transmission characteristics. with Meshes and Specular materials:
Meshes
Medium nodes should only be added to materials you've applied to meshes that define a closed volume. A single-sided plane will not work. For example, a plane representing a leaf will not work properly if a material with a medium is applied to it. The one exception is a plane representing the ground: OctaneRender treats the ground plane as an infinitely deep surface.
Specular Materials
Specular materials are the best choice when using a Medium node. When using a Specular material, set the value of the Reflection parameter to a low value because only the part of the spectrum that is not reflected can enter the object for scattering. If you set Reflection to 1, all light reflects regardless of the TransmissionA surface characteristic that determines if light may pass through a surface volume. value. If Reflection is set to 0, all light transmits through the surface, but the result is an unnatural appearance. Reflection values of 0.1 - 0.2 are good starting points.