I’m having an issue with the bloom effect on small areas flickering like crazy. Is this something I can solve, or do I have to do without bloom? I’ve searched and found one or two related threads, but nothing that helped. I’ve made a material with an emissive color that scales up as it gets closer to the player’s position. The bloom problem is mainly with the thin emissive line at the edge of the effect.
As far as I can tell I have every other post effect turned off and nothing else fancy going on. I tried messing with the bloom threshold and other settings but none of that helped. The material’s specular was set at 0 for these screenshots, though that didn’t seem to make any difference. I also have a point light very close to my pawn’s mesh which tends to cause some flickering too, but it’s much less noticeable (and impossible to see without a video).
Sorry if I’m missing something obvious, I’m a newbie who just picked up Unreal Engine about a week ago.
Thanks!
As far as I know that is an aliasing issue with too small objects/pixels. I don’t know if there is a way to actually fix that problem, but a workaround would may be to use a texture for the effect instead.
Ah. Darn, that’s the answer I was afraid of. I’m not sure how to use a texture for this, but that gave me the idea to try plugging it into the base color instead of emissive. I multiplied it up a bit, and it worked! It’s a slightly thicker and dimmer line, but that’s fine, and I can probably tweak it with lighting and stuff. So thanks!
So in other words I need to avoid making really tiny things that glow? It just seems weird that it was bright enough to trigger a bloom effect even when I cut it down to be barely visible. This is the other thing with the point light that I mentioned. I have this little rocket, with a point light just below it with it’s intensity tied to your throttle. I figured this would be more efficient than using particle lights (?). But it flickers between these:
So now I’m wondering how I can design things better to avoid the issue.
[Edit] Well, my main problem is solved, so thanks for the quick reply! That last bit was mostly me thinking aloud. I’ll mess around and see if I can figure it out by myself.
Not sure, but I think the first bloom pass is rendered in half-res (and subsequent passes half of the previous one?) , so not every pixel might be visible in the bloom pass.
Can’t remember if you can change the resolution of the passes, but might be worth checking the bloom postprocess settings.
Ahh, yes. You can change that for anti-aliasing, but there’s not option to change it for bloom.
It’s all good though. It was partly just stupid design on my part. I was just cranking up emission vectors to crazy levels instead of working out how to make the line a tiny bit thicker or the effects more visible in other ways. Now I’ve cut down the emission and combined it with changes in base color to get pretty much the same thing, but without the bloom going crazy. I mean it is sort of a bug that you have to work around, but oh well. It would be nice if there was a sample size option that you could set so one tiny speck couldn’t bloom as much as a larger lit area.