This page provides information on the MultiMatte Node in V-Ray for Blender.
Overview
With the MultiMatte Render Channel, only three colors are possible: red, green, and blue. In comparison, other matte render elements can include a multitude of colors to represent each material or object in a scene with a different color. With MultiMatte, a single R, G, or B channel can be used directly as a matte, eliminating the step of selecting the color in the compositing software. This ease of use makes MultiMatte a popular choice for compositors.
The MultiMatte Render Channel includes anti-aliasing.
To represent all the objects or materials in a scene with just the available red, green, and blue colors, several MultiMatte Render Elements can be generated for a single rendering, each with different Material ID or Object ID settings.
UI Path
||Node Editor|| > Add > Render Channels > MultiMatte
Node
Name – The name of the render channel.
Red Id – The object or material ID that is assigned to the red channel.
Green Id – The object or material ID that is assigned to the green channel.
Blue Id – The object or material ID that is assigned to the blue channel.
Use Mtl Id – When enabled, V-Ray is going to consider material IDs when calculating the MultiMatte.
Affect Matte Objects – Controls whether or not matte objects are present in the render element.
Parameters
Consider for AA – When enabled, anti-aliasing is used where possible.
Common Uses
The MultiMatte Render Channel is useful for isolating geometry in a scene. While other matte render elements perform similar tasks, MultiMatte is often quicker to use in compositing software because it can be made to include only pure red, green, and blue channels to represent objects in the scene. Compositing software often has a feature for easily selecting the red, green, or blue channels in an image for use as mattes.
As many MultiMatte Render Elements as required can be used.
MultiMatte Render Element
Matte created in composite by using only the green channel
Reflection Render Element prior to grading
Reflection Render Element with contrast added to the robot arms and a mild tint and glow applied
Original Beauty render
Reflections on the front robot arms have had their reflection tightened and a tint and mild glow added.
MultiMatte blue channel (as a mask in composite)