Pffff. Digging into this thread searching for interesting Lumen issues (exposed as feedback) is a pain… I wouldn’t want to be in the bones of the Epic Team… even reading all the messages, as I do.
Turning back to the feedback purpose,
Hi @Daniel_Wright !
Here are some observations and suggestions regarding Lumen:
Very important:
-
Please, remember the bug where multi bouncing reflections are not working in Lumen reflections + baked lighting. (Tested today on 5.4, still missing). This is the cornerstone for Lumen reflections being finally ready to work with baked lighting scenarios, which are still used/preferred by TONS of developers. (Not -only- for multibouncing mirrors, but a mirror reflecting a glossy floor near big windows, for example).
-
Add the option, cvar, material option, per object option, anything, to enable/disable emissive materials contributing to Lumen GI. Lot of users have already reported this issue, without an effective solution. There are tradeoffs, but always with a negative compensation. Emissives are officially recognised as “better to use big emissive objects” and “better to use low emissive values” to avoid massive noise, by Epic Games. But what happens if we are using a small emissive, because the object is that small? Or if we want to pushup the emissive/bloom effect in a very certain super magical object? The logical solution (if Lumen still can’t handle it correctly) would be to disable the emissive contribution and make it illuminate through a lighting source, but without loosing the emisive effect and/or bloom.
Less important:
- Reintroduce the variable “r.Lumen.HardwareRayTracing.MaxTranslucentSkipCount”. As an user pointed, it seems that the current value behaves erratically in some scenarios. Nevertheless, adding an extra variable doesn’t hurt and can provide more flexibility and optimization possibilities. I mean, “why not”?
- Increase the Lumen sampling headroom. Currently, it’s very easy to reach the maximum allowed by Lumen. It would be interesting to be able to enhance it further, not only by increasing the octahedron resolution and reducing the jittering size, but also by increasing the number of samples per pixel, for example. Useful for cinematic shoots.
- Reduce dependency on temporal accumulation. As I have tested many times and also read, Lumen is not capable of reaching high refresh rates (but it can maintain above 60fps, which is what matters). To make temporal accumulation less noticeable, high refresh rates are needed, the higher, the better, but Lumen can’t reach them. “The Lumen paradox”.
Thank you and best regards!