New static light reflection baking is difficult to work with

The 4.8 Changenotes lists :new: Rendering light shape into reflection captures for static lights

Can this be improved? This is impossible to work with if you can’t easily decide which lights get it and which do not. I have hundreds of weak ambient lights and all of them now cast reflections by default, giving me major problems with The Solus Project.

Expected behavior for me would be that if Min Roughness == 1.0 it would not bake into the reflection. It currently ignores the roughness setting it seems.

The only solution I have found is to set the source radius to a massive value, which effectively fixes it but it feels like a hack.
Optionally an ini flag to kill it altogether would be great. I looked for one but couldn’t locate one.

Here are two static lights with min roughness 1.0 that are reflecting, even though I am trying to make ambient lights with no source.

And here is a completely new empty project with a cube and 1 static weak light.
Note the extreme intensity, and strange shape for the reflection.

Hey Hourences, I’ve moved this over to our Bug Reports section so I can investigate this a little more and see if we can at the very least get a ticket in for improvement or see if there is something that can be adjusted to help get you better results. I’ll update as soon as I know more and have had time to look into this.


Do we have any update on this? It is particularly annoying, and is a visual blocker. Our whole game looks terrible now. We can’t record videos, do lighting, show it to anyone and so forth and that is a major issue.

We had someone go through the source code + shader files but we can’t really locate where this has been changed. We can’t figure it out.

This is for example how a dark corridor in the game looks right now that has a weak static light nearby. These super bright dots are also moving and flickering as you move around, making them even more obvious.

The change with how reflections work with Min Roughness is not currently supported. I’ve submitted ticket UE-19818 for this to be looked into further.

The star pattern that is generated when not using increasing the light source shape is something that we definitely want to address as well.

For instance, here was my test scene. The only way to get rid of the star pattern and remove the light shape from the capture was to increase the source radius for the light shape, but that’s not an ideal solution.

I’ll update you when I have any updates on the ticket.

Great thanks!
I hope this will still be able to make it into 4.9? From a visual perspective this is very high prio for us.

I also want to highlight that the source radius fix in reality doesn’t actually work I found out. Increasing source radius on all of our lights in a level pushed our level from 40 min preview build time to ~8 hours for a preview build. It is therefore effectively impossible to use as a fix.

Ouch! Yeah, that can be a problem. Something smaller like my test scene wouldn’t indicate that kind problem. :confused:

I’ve located the change in GitHub here:

Maybe this will help for the moment to revert some of the changes. I’ve also emailed one of the engineers to get some clarification on reverting to the older method. I’ll update you once I get a response.

Any news on this? I have a lot of “hidden” static lights in my game and all of my reflections looks crazy now.


At the moment this is backlogged due to other priorities. If you’re using a source build you can revert the changes using the information from the GitHub commit above to revert back.

From what I was told it is well contained code that can be disabled if you wish. It’s not exposed via the editor so you will have to use source to do so.