Niagara 3D Smoke Emitter indirect lighting troubles (Sep 2024)

[LieutLest]

Hi!
Does anybody know how to solve this? It’s been an issue for me since 5.3.2. Niagara 3D Smoke simulations don’t react to indirect lighting, as depicted below:

I’m working on a project where I need the smoke to be visible in shadowed areas (building shadows). When in the sun (or any other light source), everything’s dandy, but as soon as they’re in the shadow, they go completely black. Please see below:

Is there a setting I’m missing? I’ve tried everything I can. Scoured the interwebs - nothing.
I think this is a somewhat common problem, but haven’t found any fixes yet. My project’s in the City Sample. Could that have anything to do with it? Am I just donkey?

I’m in UE5.4.4.; PC Specs:
Win10 Pro OS
11th Gen Intel(R) Core™ i5-11600K processor
32.0 GB RAM
NVidia GeForce Gigabyte Aorus Master RTX 3070
ROG STRIX Z590-F GAMING WIFI Mobo

[LieutLest]

Fixed (sort of): I was reminded of lighting channels, so I looked into that. That’s the best quick solution I found so far that still conserves performance. It’s not an official solution that addresses the problem itself, but it’s the best and only workaround that I’ve managed to find that does away with the pitch-black smoke in the shaded areas. So I just:

1. Duplicated my directional light and renamed it,
2. Changed its direction and angle to face the opposite direction to the main ‘sun’ light,
3. Lowered its lux intensity to 0.3,
4. Set its Forward Shading Priority to 1 (from 0), and
5. Set its light channel to 1 (from 0)

Without the 2nd directional light:

With the 2nd directional light:

When the 2nd directional light is set to a different light channel, it only affects the smoke that is set to that same light channel, so it’s light on performance in that regard - it’s not shining on everything else.

NB: Still can’t get the blend modes, translucency, etc., just right yet, but I figured out that it has to do with Lumen, coz when I switch my viewport rendering to Path Tracing, the smoke gets appropriate indirect lighting.

Anyway, that’s the quick and dirty solution. Good luck!

[SKRUNDA (Orphan ЯТG)]

This is not a solution… how it will work with sunlight for example? Will you duplicate it?
It is messy solution. I am struggling with this same issue for some time too and couldn´t find the proper solution for it.

[LieutLest]

Ok Thank you for your criticism. Have a nice day. Good luck!

[SKRUNDA (Orphan ЯТG)]

I didn’t mean to insult you. In fact, I appreciate that someone is trying to fix this unresolved issue. I’m just saying that this solution is not universal. Thanks.

[LieutLest]

Yeah of course dude, it’s not perfect. It’s a makeshift fix. I clarified this in the post. I’m not an Unreal Engine wizard so I don’t know how to fix the blend modes and translucency of Niagara emitters and all that, I’ve tried everything, but this is the best and only solution that I’ve found that works around this impossible problem for me. If it works for you too, great.