At the moment I’m rendering an exterior animation in 2 passes. It’s a backlit scene, the sun is visible to the camera, with some atmospheric perspective and there is water in the foreground. BF+BF.
For pass 2 I have disabled the colour mapping and clamp so that I get enough range to generate my glare/bloom elements.
For pass 1 I needed to use clamp set to 20 as it was the only way to get rid of some fireflies (without tonemapping) that were causing artefacts when denoising.
Would there be a fancy way of achieving this in one pass? I tried setting MSR to 10 and it didn’t make any difference to the fireflies.
I’m also exploring options for lens flares in Fusion. I purchased these: Flare Presest for BMD Fusion, they look decent enough when paired with a dirt mask but they need a bit of work to animate the different components opacity to prevent it popping on/off as it passes “behind” the alpha channel. I’m trying to avoid using after effects to keep the process as simple a possible - I currently don’t own optical flares but may need to change tactics.
Regarding the fireflies - try activating (if already activated try decreasing) the ‘max ray intensity value’ instead of using sub-pixel mapping plus clamping and see if that makes any difference. This should reduce the effect of the fireflies, while simultaneously leaving enough information for the lens effects to function properly.
Make sure the Sun isn’t directly visible, or the reflection of the disk will nearly always create glints.
Most times the sky’s sun aura will be enough (not to mention the sun disk is really small to begin with!), while its values and large coverage should counter the tendency for stray high energy rays.
Also, any particular reason why you’re not using the LC? It too could help, and quite a bit, if nothing else by virtue of leaving you a lot more headroom for AA sampling.
Last but not least, roughen the surfaces which generate fireflies a bit more (ie. lower reflection gloss), and it’ll help.
I personally strongly dislike any form of clamping, as they sidestep the issue, instead of curing it.
There are a few *true* cases of non-resolvable glints, in most scenes, while the vast majority of fireflies is generated by incorrect scene setup, hence my qualm with just ticking on clamping and calling it solved.
Of course, if your scene falls into the incurable ones, then you’re likely already at the optimal setup as you are, with multiple passes serving different needs.