This page provides information about the Render Channel nodes in V-Ray for Blender.
Overview
Render Channels are a way to break out renders into their component parts, such as diffuse color, reflections, shadows, mattes, etc. This gives fine control over the final image when using compositing or image editing applications to reassemble the component channels. Render channels are also sometimes known as render passes.
Render channels appear in the V-Ray Frame Buffer (VFB) and can be viewed from the drop-down at the upper left corner of the VFB. They can also be saved out of the VFB as many common file formats.
Render channels are generated at render time based on the user's selection before rendering. Most render channels have parameters that can be customized to further assist the composting process. These parameters are described on each render channel's individual page.
UI Path: ||V-Ray Node Editor|| > World > Add menu > Render Channels
UI Path: ||Properties Editor|| > View Layer > Render Channels
Properties
When enabled from the View Layer tab, the render channel becomes visible in the V-Ray Node Editor World Tree and is automatically connected to the Render Channels Container, if there is one. If there is no Channels Container in the editor, one must be created so the render channels are applied to the scene. If a render channel is deleted from the Node Editor, it is automatically disabled in the View Layer tab and vice versa.
You can then view the render channel's properties either in the Node submenu of the V-Ray Node Editor or in the World tab.
To view a specific render channel's properties, see its respective page.
If you have multiple World Output nodes set up, only the render channels in the current World Output node will be displayed in the V-Ray Node Editor and the View Layer tab. See how to set up multiple World Output nodes.
Categories
All render channels are grouped into the following categories: Beauty, Advanced, Matte, Geometry, Utility, and Raw.
Beauty – Contains all the needed render channels for "Back to Beauty" compositing inside the V-Ray Frame Buffer.
When selecting the Affect All Channels option in the V-Ray Material, be aware that the information of the respective component will affect all render channels; therefore, the Back to Beauty composition will not match the RGB result from the renderer.
Advanced – Contains render channels for an advanced beautification of the light, coat, and sheen.
Matte – Contains all the needed render channels for matte compositing in the V-Ray Frame Buffer.
Geometry – Contains all the render channels responsible for editing geometries from the scene, such as Object ID, Normals etc.
Utility – Contains render channels that assist your work in the V-Ray Frame Buffer.
Raw – Contains render channels that concern RAW layers.
The applied render channels are found in the VFB's dropdown menu. The new render channels become visible in this list after a new render is started.
Render Channels
V-Ray supports the following render channels. All render channels support native V-Ray materials.
In order to render a correct Raw render pass, you need to also render the corresponding main channel and filter. For example, Raw Reflection will require you to render the Reflection and Reflection filter. For Raw GI, you need GI and Diffuse, etc.
Beauty
| Render channel | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| Background | 16bit/32bit | Image background, such as any Background Texture specified in the Globals Rollout. |
| Lighting | 16bit/32bit | Diffuse direct surface lighting. |
| GI (Global Illumination) | 16bit/32bit | The diffuse surface global illumination. Only present if Global illumination is enabled. |
| Reflection | 16bit/32bit | All indirect reflections from a surface. |
| Refraction | 16bit/32bit | Refractions through a surface. |
| Specular | 16bit/32bit | All direct specular highlights coming from a surface. |
| SSS | 16bit/32bit | Renders just the subsurface part of the VRaySSS2 material on a separate layer. |
| Self-Illumination | 16bit/32bit | Self-illumination of the surface. |
| 16bit/32bit | The caustics on the material. These caustics are present only when the Caustics option of V-Ray is enabled. This channel does not include GI caustics. | |
| 16bit/32bit | Atmospheric effects, such as Environment Fog. |
Advanced
| Render channel | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| Coat | 16bit/32bit | Isolates the reflected light in the scene. |
| Coat Reflection | 16bit/32bit | Indirect reflections coming from the Coat layers of the V-Ray Material used in the scene. |
| 16bit/32bit | Extracts the contribution of a user-defined light or a set of lights in the scene as a separate render channel. | |
| Sheen | 16bit/32bit | Isolates the reflected light in the scene. |
| Sheen Reflection | 16bit/32bit | Indirect reflections coming from the Sheen layer(s) of the V-Ray Material(s) used in the scene. |
| Toon | 16bit/32bit | Creates a toon-like effect on the render. |
| Diffuse | 16bit/32bit | Pure diffuse surface color. |
| Shadow | 16bit/32bit | Diffuse light that is blocked by other objects. |
| Total Light | 16bit/32bit | Total lighting in the scene, both direct and indirect. |
| Reflection Filter | 16bit/32bit | Reflection filter (the color by which the raw reflections are multiplied to give the final surface reflection). This may be considered an alpha channel for reflections. |
| Refraction Filter | 16bit/32bit | The refraction filter mitigates the raw refraction layer. This render channel returns the color by which the raw refractions are multiplied to give the final surface refraction. This may be considered an alpha channel for refractions. |
| Reflection IOR | Used to enhance or reduce Fresnel IOR effects in the final composite. | |
| 16bit/32bit | Returns a float value that corresponds with the Reflection Glossiness value of an object's material. | |
| Reflection Highlight Glossiness | Returns a grayscale image that corresponds to the value in the Highlight Glossiness of the materials in the scene. | |
| Refraction Glossiness | 16bit/32bit | Returns a float value that corresponds to the Refraction Glossiness value of an object's material. |
| Metalness | 16bit/32bit | Returns a grayscale image that corresponds to the metalness values of the materials in the scene. |
| Coat Filter | 16bit/32bit | Reflection filter for V-Ray Material Coat layer. |
| Coat Glossiness | 16bit/32bit | Returns a float value that corresponds with the Coat Glossiness value of the V-Ray Material Coat layer. |
| Sheen Glossiness | 16bit/32bit | Returns a float value that corresponds with the Sheen Glossiness value of the V-Ray Material Sheen layer. |
| Sheen Filter | 16bit/32bit | Reflection filter for V-Ray Material Sheen layer. |
| 16bit/32bit | Stores Toon Specular reflection (highlights) information calculated from the Toon Material and Toon Material Node | |
| Toon Lighting | 16bit/32bit | Stores direct lighting information from lights in the scene that hit the Toon Material and Toon Material Node. |
Matte
| Render element | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| forced 32bit (for multi-channel files) | Uses the Cryptomatte convention by Psypop to encode mattes into multichannel OpenEXRs. | |
| 16bit/32bit | Renders only the object(s) assigned to a user-specified V-Ray compatible material. The material can be a top-level material or a sub-material of a Blend Mtl. | |
| Multi Matte ID | Isolates objects with specific Multi Matte IDs for compositing purposes. | |
| Multi Matte | Uses a single R, G, or B channel to create a matte. | |
| – | Returns solid un-shaded colors to represent numerical identifiers set through that object's Attributes, Object Property, or assigned material. Useful for selection masks. EXRs and .vrimg formats are stored as integer values. | |
| Object Select | 16bit/32bit | Renders only the object(s) called out with a specific Object or Material ID. This effect is reversible to create a render element that excludes a particular object or objects according to Object or Material ID. |
| Render ID | – | Node render ID of the object that contributes most to the pixel value. |
| Material ID | – | Material ID of scene objects. |
| Matte Shadow | 16bit/32bit | The matte shadow part of the image. |
Geometry
| Render element | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| Bump Normals | 16bit/32bit | Normals generated by bump maps in screen space (which is not the same as camera space). Use the VRaySamplerInfo utility texture node to get the normals in camera, world, or object space. |
| Normals | 16bit/32bit | Surface normals in screen space (which is not the same as camera space). |
| 16bit/32bit | Surface velocity of an object. This render element is useful for generating motion blur in post-production. | |
| Z-depth | forced 32bit (for multi-channel files) | Z-depth of surfaces in the scene. |
Utility
| Render element | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| Coverage | 16bit/32bit | For each pixel, the final values for the render element are taken from the object that makes the largest contribution to that pixel. |
| DR Bucket | 16bit/32bit | Displays the machine that rendered each bucket when using distributed rendering with the Bucket Image Sampler. |
| Extra Tex(ture) | forced 32bit (optional for multi-channel files) | Renders the entire scene with a single defined texture mapped on all objects. |
| Sample Rate | 16bit/32bit | Shows an image where the pixel brightness is directly proportional to the number of samples taken at that pixel. |
Raw
| Render channel | Color Depth of EXR floating-point channels | Description |
|---|---|---|
| 16bit/32bit | Raw diffuse direct illumination before it's multiplied by the diffuse surface color. | |
| Raw GI | 16bit/32bit | Raw diffuse global illumination (not multiplied by the diffuse surface color). Only present if Global illumination is enabled. |
| Raw Total Light | 16bit/32bit | The sum of all raw lighting, both direct and indirect. |
| Raw Reflection | 16bit/32bit | Pure surface indirect reflection before it is multiplied by the reflection filter color. |
| 16bit/32bit | Pure surface refraction before it is multiplied by the refraction filter color. | |
| Raw Coat Filter | 16bit/32bit | Creates a solid mask showing the areas of reflection in the Coat layer without being affected by Fresnel. |
| Raw Coat Reflection | 16bit/32bit | Pure surface indirect reflection from a V-Ray Material Coat layer before it is multiplied by the reflection filter color. |
| Raw Sheen Filter | 16bit/32bit | Holds information similar to Sheen Filter RE, but without being affected by Fresnel. |
| Raw Shadow | 16bit/32bit | Raw light that is blocked by other objects. |
16bit/32bit | Pure surface indirect reflection from a V-Ray Material Sheen layer before it is multiplied by the reflection filter color. |