This page gives some basic details about the Raw Shadow render element and explains how it is used.
The Raw Shadow Render Element stores information about cast shadows calculated from the lighting in the scene. It is a "reverse" image in the sense that white areas indicate shadows while black areas indicate no shadow.
This render element is enabled through the Render Elements tab of the Render Setup window in 3ds Max and displays its parameters in a rollout at the bottom of the window:
VRayVFB – When enabled, the render element appears in the V-Ray Virtual Frame Buffer.
Deep output – Specifies whether to include this render element in deep images.
Color mapping – Applies the color mapping options specified in the color mapping rollout (Render Setup window > V-Ray tab) to this render element. This option is enabled by default.
Multiplier – Sets the overall intensity of the render element, where 1.0 is the standard multiplier.
Denoise – Specifies whether to denoise this render element.
The Raw Shadow Render Element is useful for changing the appearance of shadowed areas, after rending, inside a compositing or image editing application. In the example, the Raw Shadows are added (plus) to the VRayRawLighting Render Element. See how the render looks before and after compositing.
Underlying Compositing Equation
Shadows can be both added and subtracted at a composite level without rerendering using the Shadow Render Elements.
Shadows can be color corrected using the Shadow Render Elements.