Firstly thank you to everyone for your feedback. Hugely appreciate it.
So I tried a few more of your ideas in the scene and this is my findings so far…
“Increase the “Final Gather” Setting in your Post Process Volume to get rid of the splotchy GI. 5 works good on my system, moving it to 6 really hits the performance”.
It seemed to make no difference in clearly up the splotchy results with a setting of 5…6…8…12…30…75…or even 100! (pictured)
(The Post Process is definitely enabled as the setting to adjust Final Gather becomes disabled if its not. Ive also tried it on a confined volume and an infinite unbound, and still no difference in the results?).
Next, I went back to the kitchen shot and tried:
“You can try adding a plane or box just above the ceiling and/or enable double sided materials.”
I added a box above the roof plane to see if it would have any effect. Unfortunately not. I then set the walls and ceiling marked with an X to use a double sided material. As you can see, same result.
I then tried:
“Suggest adding more direct light, bigger windows or secondary light sources to try and hide this.”
So I tried absolutely blowing out the lighting to see if I could nuke that noise, but even at 80.0 lux, the noise is still there!
As for option 2, unfortunately the design is fixed and I cant make any structural changes to the build.
I think maybe the secondary light might help, (I haven’t tried that yet). I was really trying to find a way to tweak the setings to get a natural response from Lumen without having to help it or fake lighting to get the right result.
(I guess the next question is, are people still using rec lights to help their interior scenes?)