Description

Even when the max roughness for raytraced reflections is set to 1, they seem to be blended away at far below that value. For projects (e.g. film,vfx) where quality trumps speed it would be valuable to be able to use only raytraced reflections for all roughness levels.
Unsure about regression.

Steps to Reproduce

Quick repro

  1. Open the project in 4.26
    [Link Removed]
  2. Open the Black Material in the content browser
  3. Set the Roughness to1.0
    Result: When the roughness goes above about 0.6 the raytraced reflection diverges from the path tracer. At 0.8 roughness the raytraced reflection all but disappears.
    Expected: Raytraced reflection would basically match the path tracer.

Longer Repro:

  1. Create a new blank film project raytracing enabled.
  2. Delete everything but the floor and create a sphere above it.
  3. Create a post process vol, enable infinite, ray traced refl, max roughness 1.0, samples 8
  4. Create two materials, one with roughness = 0.5, spec = 1.0, one emissive = 1.0
  5. Apply the reflective mat to the floor, emissive to the sphere.
    Compare with path tracer, looks good!
    #Set the roughness to 0.8
    Compare with path tracer, doesn't match!

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-102279 in the post.

9
Login to Vote

By Design
ComponentUE - Graphics Features - Lumen
Affects Versions4.26
Target Fix4.27
CreatedOct 30, 2020
ResolvedApr 28, 2021
UpdatedApr 27, 2022
View Jira Issue