Bloom and glare overhead

[romullus]

How much penalty in render time do we get if leaving bloom and glare turned on during rendering? If it's more than couple percents, maybe it's worth to keep it off and turn it on only after rendering is finished?

[Frood]

I was asking myself the same recently. Though I have no data, it feels to be quite some amount.

I wonder if B+G is calculated periodically in the following situations:

- Render via Backburner
- Minimized Max
- Minimized cVFB

Or is it just linked to cVFB refresh time?

Good Luck

[Ondra]

while the overhead should be small enough, there is no reason ever to calculate it on DR slaves. I have disabled it for corona DR

[Cheesemsmsm]

If I turned it off, I always forget to turn it on before saving. And then I realized that I forgot to turn it on when I open the file in photoshop.
I have to re-open the scene, resume render, waiting for calculating GI and denosing, turn on bloom and glare and save... It takes ages for large scenes.

so I always turn it on lol

[martinsik]

In the worst case scenario (short rendering with high resolution) the computation of bloom and glare may completely overtake 1 logical core.
So if you have 16 logical cores, you may loose 6% of rendering power (or even twice more if you have less physical cores and use hyperthreading).

On the other hand, if you render for long time and don't change the bloom and glare parameters during rendering, the period of updating bloom and glare will get longer and longer up to 30 seconds,
and thus the overhead will be minimal.

[romullus]

Thanks for the answer. Long time rendering is what i'm interesting about.

[martinsik]

I was asking myself the same recently. Though I have no data, it feels to be quite some amount.

I wonder if B+G is calculated periodically in the following situations:

- Render via Backburner
- Minimized Max
- Minimized cVFB

Or is it just linked to cVFB refresh time?

Good Luck

If cVFG or Max is minimized, bloom and glare is not updated.
If cVFG is active (not minimized), bloom and glare is refreshed, but not as often as cVFB itself.

[Frood]

Thanks for the detailed insights - calming to know about that long run behaviour indeed because it affects BB jobs as well.

Good Luck

[Nejc Kilar]

Good to know! I would presume these numbers are with the 1.6 daily (i.e the speed has been further improved) and not with 1.5?

[Saif]

What about if you rendering an animation, if you disabled it you will get faster render, but with no bloom and glare ?

[romullus]

Well, with animations you have no choice, it's either on or off, unless you're willing to sit in front of your pc and constantly turn on and off B&G while frames progresses :]

[Saif]

Sounds fun