Semi-simple question, is there a way to override the Level Scale in relation to all dynamic lighting and rendering metrics (lumen, VSM, raytrace samples etc) — the exact same way as what legacy Lightmass Static Lighting Level Scale did when baking lightmaps and light probes?
This was a common method to use when baking with lightmass to bake for large maps with far distance vistas, at the trade-off of reducing lighting accuracy/fidelity (typically done for other space games, giant mech games, flight sim games etc.)
Right now it is near impossible to juggle and fine tune all the cvars involved to do this, with many render settings not being easy to find, understand or modify.
Things we’ve tried:
Matt Oztalay has mentioned to use “View Distance Scalability” settings found in config, but it wasn’t apparent as to how to find and use these to achieve the same results as Lightmass Static Lighting Level Scale. We also tried using far field lumen representation, but this didn’t seem to kick in at a distance as we hoped.
This is currently one of the biggest blockers to considering using features like Lumen for mid and high-tier hardware hitting ~60 FPS.
Hope to have some insight or have the Level Scale feature considered.
Hey there again! Thanks for your patience while I’ve been away. View Distance Scalability is probably not quite the way to go for the kind of distances and heights that y’all are looking at, sorry for leading y’all astray. You’re right that the Lightmass Level Scale settings only apply to lightmap baking and aren’t relevant or used by Lumen at all.
On the content side of things, you might be able to recreate the results of the Lightmass Level scale with a combination of the following settings on a PostProcessVolume:
Lumen Scene Lighting Quality (down)
Lumen Scene Detail (down)
Lumen Scene View Distance (up)
Max Trace Distance (up)
Scene Capture Cache Resolution Scale (down)
The point being to be able to increase the Lumen Scene View Distance while maintaining consistent performance but at a lower quality (more or less the same result as the lightmass level scale).
This’ll probably get you further in the giant mech example, but I’m not wholly convinced that this’ll get you everything you need for high-flying flight or space sims. Trying to extend the Lumen Scene View Distance down to ground level from 36,000 feet is already going to be too expensive, let alone getting those results visible out in front of the plane.
So that’s why I think it’ll be important to get the Lumen Far Field working right. When you say that it’s not kicking in at the distance you’d hope, could you share some screenshots of the issue and your farfield settings? I can mark this question as confidential if you need me to.
I have tried those Lumen Scene settings prior. The Max trace distance helps, but unfortunately both quality settings seem to be relative to screen space, not world space?
Attached is a block-out screenshot to show the types of visual issues being faced when dealing with larger-than-life camera compositions. One scene has a typical character (and environment) at normal 1.0x height with default lumen settings. The other shot is showing the same scene and character blown up to 400% in scale, with the Lumen render distance 4.0x and quality settings set to 0.25x
As you’d expect, the noise is much worse, and there’s going to be a whole range of other scalability settings to tweak too regarding shadows and other quality settings.
Is there any cvar that can reduce Trace Distance Accuracy? That would be the type of tweaks that would solve it, Would ideally need to increase max distance and reduce distance accuracy across other features too, like volumetric fog distance accuracy, shadow distance accuracy. etc. Would of course cause higher chance for light leaking, but we can work around that.
Here’s an A/B test screenshot. hope it makes sense:
Hey there! I set up a simple test similar to yours, but I wasn’t able to reproduce the issues you’re seeing in your inset camera view in the screenshots you sent over. I might recommend tuning the Lumen Scene Detail value a bit more, because I was noticing that with a value of .25 a few of the more distant large walls were losing surface cache coverage. I also remember there being some issues with SWRT lumen and static meshes that were scaled considerably larger than their original size, I don’t suppose you’ve made the switch over to HWRT yet, have you?
I have tried Lumen Scene Detail, but again, this seems relative to screen space. Since it’s a distance-related issue, I need something based on world space. Let me know if you need a test scene since you weren’t able to reproduce. And yes, HWRT is on.