Rectangular Area Lights require extremely high values in order to illuminate Volumetric Fog and Volumetric Materials. This means they do not appear to match the output of other light types of identical intensity.

To confirm that volumetric fog works at all with Rect Lights, I changed the Intensity Units to Unitless, set the Intensity to max, then changed the unit back to Candalas. This set the Intensity value far higher than the maximum for Candalas and allowing the illumination of the fog to be seen.

Steps to Reproduce
  1. Open QAGame
  2. Open Tm-VolumeMaterials_Stationary
  3. Add a RectLight to the level
  4. Expand the Light section in the Details Panel and enable the Cast Volumetric Shadow option
  5. set Intensity to 5000
  6. Set Intensity Unit to Unitless

Expected: Rect Light illuminates fog at about equal to the pointlight nearby, which shares the same Intensity
Result: Rect light does not appear to illuminate the fog

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ComponentRendering - Features Teams
Affects Versions4.204.22
Target Fix4.26
Release Commit8370517
CreatedJul 9, 2018
UpdatedMar 3, 2020