HD
I mainly render in hd for interior scene
192x1080
400 samples
15 min
4K
But I tested myself and with
3840x2160
100 samples
15 min
The 4k is 4 times larger then hd, but rendering it with 4 times less samples, takes the same amount of time.
better resolution gives the samples a bigger area to work with is the reasoning.
But if this is the case everbody should be rendeering in 4k (and could use less samples). right ? or depends?
If you take your 4k render and scale it to HD, you’re basically doing the same thing as the HD render at 400 samples.
Sampling is basically trying to average value for each sample.
maybe at 4k it’s a bit more forgiving as it’s harder to see the pixels.
I think it’s best to render to the desired resolution unless you have an issue. Sometimes it’s faster to render at a lower resolution and upscale the result.
Anyway, to get a real answer you should run some tests, try to see what render works better given the samples, if it’s not obvious you can try with lower samples…
The higher resolution can help get better denoising (even with fewer samples). The fine details will be better preserved and any remaining temporal flickering will be smaller and more even.
From what I have heard, some big VFX studios even use this.
I have tested it and 4k with 100 samples seems sharper. Little more detail. No temporal result yet. Need to to render animation for that, takes more time.
So far I am for the 4k choise.