Tested in //UE4/Release-4.27 CL#18319896

Ray Traced Translucency causes artifacts when rotating a Static Mesh in the 'Open World' level when moved far away from the center of the map. The Artifacts begins to appear roughly at the edge of the last World Partition Cells once the mesh is rotated.

DumpGPU will be added to the comments.

Steps to Reproduce
  1. Create a new Blank project with Ray Tracing enabled
  2. Create and open a new Material named M_Translucency
    1. With the Result Node selected
      1. Set Blend Mode to Translucent
      2. Enable Two Sided
      3. Set Lighting Mode to Surface TranslucencyVolume
    2. In the Material Graph:
      1. Create a Constant Vector 4 (4+Left Click) then connect it to Base Color
      2. Create a Constant (1+Left Click) then connect it to Metallic, Specular, and Roughness
      3. Create a Constant (1+Left Click) set it to 0.5 then connect it to Opacity
      4. Create a Constant (1+Left Click) set it to 1.0 then connect it to Refraction
    3. Apply, save, and close the Material
  3. Add a Post Processing Volume to the level
    1. In the Post Processing Volume's Details panel: 
      1. Set Extent to Unbound
      2. Enable Translucency and set it to Ray Tracing
  4. Add a Cube to the Level
  5. Apply the M_Translucency material to the cube
  6. Set the Cubes Location on the X or Y axis to ~1,000,000.0
  7. Focus the Cube in the Viewport
  8. Rotate the Cube on the Z axis

Expected Results:
Ray Traced Translucency behaves as it does before the cube was moved or rotated.

Actual Results:
Lines and Artifacts over the surface of the cube.

Have Comments or More Details?

There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-157005 in the post.

Login to Vote

Won't Fix
ComponentUE - Graphics Features
Affects Versions5.0.2
Target Fix5.1
CreatedJun 17, 2022
ResolvedJun 22, 2022
UpdatedJun 22, 2022