Point Light source problem in glass reflections when source radius is greater than 0 and translucency is set to "Raster"

Development Rendering
1

The problem is: the point light source shows in reflections even behind a mesh when translucency is mode is set to Raster.

In this example, the source radius is set to 26, the glass material of the wall comes from the content of the Datasmith plugin. The point light sits in the lamp and has an IES texture.

Screenshot 1:
Material Lighting Mode = Surface Forward Shading
Translucency Mode = Raster

Screenshot 2:
Material Lighting Mode = Surface Forward Shading
Translucency Mode = Raster
Light sits in the sphere (two sided material)

Screenshot 3:
Material Lighting Mode = Surface Forward Shading
Translucency Mode = Ray Tracing

Screenshot 4:
Material Lighting Mode = Surface Translucency Volume
Translucency Mode = Raster

Of course I could use one of two workarounds but you just have to make compromises.

With MLM set to Suface Forward Shading and TM set to Ray Tracing the reflections at the floor behind the glass are gone.

With TM set to Ray Tracing additionally some distant objects are no longer in the shadow.

I would very appreciate any other ideas to get that right.

01Point_Light_source_26_Raster_SFS
01Point_Light_source_26_Raster_SFS1920Ă—1063 136 KB

02Point_Light_source_26_Raster_SFS_Sphere
02Point_Light_source_26_Raster_SFS_Sphere1920Ă—1063 119 KB

03Point_Light_source_26_RT_SFS
03Point_Light_source_26_RT_SFS1920Ă—1063 137 KB

04Point_Light_source_26_Raster_STV
04Point_Light_source_26_Raster_STV1920Ă—1063 136 KB

TIA,
urig

2

No idea anyone?

3

I reported this in the Lumen thread a while back, no idea if it will be fixed as I confirmed it is still broken in 5.4 preview.

Only real advice I could give you is to set the specular scale of the light to 0 so that it doesn’t render in reflections at all.

Other than that there isn’t really anything you can do except wait for Epic to fix it, if ever.

1 Like
4

Thanks for your reply. I tried the “specular scale” method and as you mentioned there are no reflections anywhere. I prefer to go with “no reflections behind the glass”. I can live better with this until Epic fixed this bug.