Hey, I have a problem with ray traced light reflections in glass materials.
as you can see, normal objects like a cube are displayed correct in the reflections, but a rectangular light always shows up kind of jagged…
its the same problem with a simple plane with a glass material on it so i dont think it has something to do with the geometry…
doesn anyone have any idea what could be the problem?
Its Unreal 4.27.1 but it also showd up earlier in 4.26
thank you for any help!!
Notice you have Screen Space Reflections on in the material. It may be overriding or mixing with the ray traced result, which could be a part of how it’s jagged. Is there a post process volume in the scene? If yes, try modifying the ray traced reflections and translucency in it, and increasing samples for every feature that involves the ray tracing.
thanks for your answer! i turned off SSR, nothing changed. post process changes did also not change anything. 
i really dont know whats the problem…
It could be the rectangular light or plane is not getting anti-aliasing applied in its reflection image. I’ll look around the engine and docs for cvars that can change that, or in the preferences / project settings. One setting to enable on the glass object is “Use High Precision Tangent Basis” in its Mesh Build settings, under LOD0. Another is in Project Settings > Engine > Rendering, go to GBuffer Format and select “High Precision Normals” from the dropdown. It changes the encoding of normals to 16 bit instead of 8 which is default, so it improves the quality of reflections in reflective surfaces.
What are the skylight and directional lights’ mobility?
