This page gives an overview of the matte render elements that may be generated through V-Ray and how they are used in compositing.
A matte render element is an aid for selection masks for the compositing process. The term matte refers to a technique for layering two or more images where parts of each image are masked or blocked from the final composite.
When compositing, it can be useful to mask an individual scene object or material in order to include or exclude it in a specific post-production process.
A matte render element consists of values and/or solid colors that facilitate easy selection for masking or control purposes.
List of Matte Render Elements
The colors and values generated for each matte render element depend on the type of render element is used:
- Cryptomatte Render Element - Uses the Cryptomatte convention by Psypop to encode mattes into multichannel OpenEXRs.
- Multi Matte - Creates selection masks based on an Object ID or Material ID
- Ojbect ID - Returns solid un-shaded colors to represent numerical identifiers set from the V-Ray Geometry Properites. Useful for selection masks. EXRs and .vrimg formats store as integer values.
- Material ID - Material ID of scene objects.
- Render ID - Node render ID of the object that contributes most to the pixel value.
While each matte render element has its uses, the Multimatte Render Element is the most common choice because of its versatility and the usefulness of the render elements it creates. The Render ID Render Element is the least common; it is used only for specialized purposes.
Matte elements can be combined with or subtracted from a composite to generate complex mattes.