Spectral Remove Fog
Spectral Remove Fog separates the underlying scene color from the fog already composited over it. Use it when custom post-processing should affect the scene without also changing the fog's color and lighting.
For example, you might want to tint the surfaces in a scene while preserving the original fog. Remove the fog, apply the tint, then restore the fog with Spectral Reapply Fog.
Material setup
Use Material Domain: Post Process and Blendable Location: Scene Color Before DOF. Add the material to your post-process setup. This is not a surface-material node and does not create or remove fog actors.
Use the RGB color from a SceneTexture node set to PostProcessInput0 as the starting image:
PostProcessInput0
→ Spectral Remove Fog
→ your color processing
→ Spectral Reapply Fog
→ Emissive Color
The fog nodes read Spectral's shared fog-composition texture internally. You do not need to wire a separate fog texture into them. The matching renderer integration must be active; use the required shader hooks and a supported path.
Inputs, output, and properties
| Connection | Meaning |
|---|---|
| Scene Color input | Required RGB scene color that already contains fog. Normally PostProcessInput0. |
| Color output | RGB scene color after removing fog lighting and attenuation. |
There are no editable density, quality, strength, or UV properties on the node. An unconnected Scene Color input causes a material compilation error.
What removal means
Fog both adds scattered light and reduces how much of the scene you can see through it. Remove Fog accounts for both: it subtracts the added fog color, then compensates for the lost transmission. Simply subtracting a fog-color texture would leave the underlying scene too dark.
The node prevents negative recovered colors and limits division by very small transmission values. Those safeguards avoid invalid arithmetic; they cannot recreate detail that the rendered image no longer contains.
Very dense fog can hide the scene almost completely. Removing it afterwards cannot recover detail that was lost during rendering, and compensation can amplify small errors. This is a compositing tool, not a second unfogged scene render.
Common mistakes
- Using a different post-process stage from Scene Color Before DOF.
- Supplying an arbitrary surface color instead of the scene image.
- Adding fog back by hand and then also using Reapply Fog.
- Warping scene UVs while expecting the node's same-pixel fog sample to follow that warp.
The straightforward workflow is a color operation on the current pixel. Spatial effects need matching scene and fog sampling; these nodes do not expose a UV input for that.
Updates
Graph edits update after applying the material and do not need a lighting rebake. Changing the baked lighting that illuminates the fog is a separate bake operation. See Fog for Spectral Fog Volume and Exponential Height Fog support.
Fog