"Ray Termination" render setting

[philip_nel]

I'm rendering a massive masterplan with a RTX 3060 - struggling because it's running out of memory.

When checking "ray termination" under render settings, I can actually move and render a bit quicker too. Do you ever use it?
Does it introduce more noise in render - temporal or spatial noise?

I'm already struggling with temporal/crawling noise on vegetation as my render sample are only 30 to get appropriate render times.

Any more tips to limit memory crashes? Already rendering at a lower resolution and upscaling later.

[npg]

If your scene uses displacement, try reducing the displacement tessellation level in Preferences.
There is a texture LOD bias setting in the render settings panel (Advanced) - try setting it to 1. It should reduce texture memory usage a bit.

Ray termination is expected to increase noise, but the denoiser can probably handle it.
If you have many light sources (dozens, hundreds) try enabling "reservoir resampling" if you haven't. It should clean up better with the few sampling passes that you use. In this case you can reduce light tree samples to 1 if you had them increased (affects secondary bounces).

[philip_nel]

Thanks for the quick reply npg.

No displacement, but will change the material LOD to 1 and see if it makes a difference - it's this setting correct? See attached.
Will it have a noticeable visual effect in the rendered sequence?

[npg]

Textures may become slightly more blurry - this will use a smaller MIP level. It may also be unnoticeable, especially if you use a value between 0 and 1. But start with 1 to see how much memory it will save.

If the scene uses a bit more than the available VRAM the OS will swap things around and will manage to continue rendering, but at a significantly reduced frame rate (you may have to disable "safe gpu allocations" to allow that). In this case a small reduction in memory use could be key to improving performance because it may allow the scene to entirely fit in VRAM. If the overflow is much bigger it may just crash. And in this case a small reduction won't help much because the scene still won't fully fit in VRAM.

[npg]

BTW you can even set tex LOD bias to 2.0 if you type it in manually, but this will definitely make things blurry.

[philip_nel]

Ok, thanks - yes save gpu allocations are already disabled.
I'll play around with the LOD setting and see if I'm happy with the quality.

Days like this I dream about a 24GB RTX...