Comparing Ray Traced/Lighting Renders in Unreal 4.27

Some shots I want to implement into my project have camera movement that creates issues with pop in for screen space effects. So I activated some of the ray tracing effects to test how they perform, and to compare the final image quality.

I had to adjust all the lighting once I enabled ray tracing, as it soon became apparent, that I had set the ambient sky light levels too low, and was overcompensating the exposure to brighten the image, which in turn was creating issues with the colour of the image.

Issues with noise with RT Global Illumination

No RT GI | RT GI 'Brute | RT GI 'Final Gather' | RT GI 'Final Gather' with more samples

No RT Global Illumination

RT GI 'Brute Force'

RT GI 'Final Gather'

'Final Gather' more samples

After some experimentation, the issue was with the material. I'm not entirely sure what causes the noise issue, but certainly there is an issue with how some materials are setup.

Changing the Material

Even after changing the material to one from the Megascans library, there is still a small amount of noise/flicker from the Ray Traced GI. The noise can also be seen on the column and window frame - albeit much fainter - and this could be the cause of the minimal flicker remaining on the changed wall material.