Help! Particles invisible with ray tracing

Hi there

I’m using cascade particles from an older project… originally created in 4.18, I migrated them into a new project that is using 4.25.3. They looked fine when I drop them into a map (translucency was set to raster) but once I turn on ray tracing translucency in the PostProcessVolume they become invisible. I’m using a RTX 2080 card. Is there something I’m missing? Is there some trick to getting particles to work with ray tracing? Is there a magic switch I need to switch on or off? I’ve also tried the same translucent material on Niagara particles, but it actually does the opposite, makes them solid and over blown looking and looks like its adding refraction even though the material doesn’t have any refraction. Any help in the matter would greatly be appreciated… pulling my hair out :frowning:


Hello and hope this helps
Good NEWS it WORKS sort-of
I have recently accomplished the impossible with the help of this link:

or you can just copy and paste this title in Google:
Fundamentals of Ray Tracing | SIGGRAPH 2019 | Unreal Engine

Look at my Post Process Settings and Game Image Sample:
Great Results with Both Ray Tracing and Cascade Particles, the ONLY ISSUE is the TRANSLUCENCY but it still looks Great

Project Settings: Check these Four (4) Settings then Restart Engine
[FONT=Liberation Serif]**1 DirectX 12 (under **Platforms – Windows Targeted RHIs)
[FONT=Liberation Serif]**2 Ray Tracing (**under Engine – Rendering)
**3 High Precision Normals (**under Optimizations GBuffer)
4 [FONT=Liberation Serif]**check Reflection Capture Resolution and set to 1024 (**under Engine Rendering - Reflections)

Lighting Settings:
ALL Lights including Directional Light and even Sky Light must be set to MOVABLE
Check Use Area Shadows for Stationary Light (under Lightmass)

Post Process Settings:
Ray Tracing Global Illumination type i have set to Final Gather (optional)
Translucency type i have set to Raster (important: if it is Ray Tracing the Cascade Particles will NOT SHOW but everything else WORKS)

Hi, happened to encounter the same problem, particle system do not work well with raytracing translucency. I have to use multiple postprocess Volume boxes to ease the problem. The volume with particles is set to raster translucency, another volume where there are massive glass walls is set to Raytracing translucency for better reflection.

However, the short coming is when I standing in the raytracing volume box looking towards the particles(waterfall in my case), they are still not visible. once I stepped out the box the particles showing again. I am guessing Epic can’t fix the problem ever since raytracing has been available. To further ease the “looking towards” problem, I may try use static mesh with moving texture as LOD to the particle waterfall, since they are not effected by the turning on/off of the raytracing translucency.