This page gives some basic details about the Raw Reflection render element and how it is used in compositing.
The Raw Reflection Render Element stores reflection information calculated from the materials' reflection values in the scene. Surfaces with no reflection values set in their materials will contain no information in the render element, which means these areas will render as black. When the Raw Reflection Render Element is multiplied by the Reflection Filter, the Reflection Render Element is produced.
Raw Reflection gives the full reflection of objects reflecting in the scene, while the reflection filter Reflection Filter sets how much of that reflection should come through in the composite. In other words, the filter defines the strength of the reflection, while the raw image defines what is being reflected in the image. When these two elements are multiplied, the true level of reflection is given as the Reflection Render Element. By using these component parts of the reflection, you can fine-tune the reflection in your final composite.
||out Network|| > V-Ray Render Elements node > V-Ray > Render Channel > Color Channel > Type > Raw Reflection
The parameters for this render element appear in the V-Ray RenderChannelColor render channels node.
Denoise – Enables the render element's denoising, provided the Denoiser render element is present.
Consider for Anti-Aliasing – When enabled, anti-aliasing will be used where possible.
Color Mapping – When enabled, the Color Mapping options in the render settings will be applied to the current render channel.
Derive Raw Channels – Generates data in the raw channels by combining the respective color and the filter color channels.
VFB Color Corrections – Applies the post render color adjustments made from the VFB.
This render element is not supported with V-Ray GPU rendering.
The Raw Reflection Render Element is useful for changing the appearance of reflective scene elements in compositing or image editing software after the scene is rendered. Below are a couple of examples of its use.
Brightened Reflection Render Element
Brightened and warmed Reflection Render Element
Warmed and raised reflections
Underlying Compositing Equation