Noise problem interior scene / Render times

[Ben Janowitz]

Hey guys,
pretty much new user here.
I'm struggling a bit understanding how Fstorm works in terms of samples/noise treshold etc...
First I don't have multiple GPU, just one GTX 780m 4GB on an iMac 27 (through bootcamp W10), so I can understand that render times are quite high (9 hours at 3000x2500), but I was expecting much lower than V-ray or Corona and I think they will be, but as soon as I understand the engine.
I'm currently working on an interior scene (a commercial one, so I'm not going to post the scene, but I'll try to be as much detailed as you ask) it's a store, with just one large glass entrance and inside full of spotlights (attached on the ceiling and inside the shop windows).
The scene it's light with a HDRI map in the environment, all setted as Daniel Reutesward explained in his post months ago, and I've assigned a light material with a power of 50 to the spotlights.
With the default settings (the same Daniel uses) the scene is very noisey and really dark. I have to crank the exposure of the environment at least at 12 and the exposure of the HDRI map too.
My first question is:
How do I know how much samples render samples I need? more mean more quality? speed? I've seen Johannes in his tutorials crank them to 10000 and daniel just 1000 and have pretty much the same results...confusing.
Same goes for the light samples, how do I set them? more lights I have inside the scene means more samples i need?
I know that using portals speed up the whole thing, but is realism losing it?
Thanks!

[mitviz]

hi, more samples means longer render times and there is not way of knowing how long a scene will take without making tests, its not like vray, sometimes for a scene 1000 samples will give 100 percent noise clearance at a particular noise threshold and sometime 10000 is needed, depends from scene to scene, so no way of knowing that, sorry i wanted to know the same thing not long ago, karba needs to somehow come up with a solution for this. for light samples more lights you have more light samples needed but i usually leave mine at 4 or 8, never seen much difference in quality or speed at 4 or 8, as for hdri lights, all depends on the hdri, some hdri give nice brightness and some no, try using same one he did or just take some from grant warwick, use the sample ones to test, they are pretty nice. as for portals, well it makes the scene brighter but i have had better results using just plane lights in the windows, that non physical and you should not do this but hey, it works for me and less noise.

[RobSteady]

Try this:

• Use portals in every opening (simple plane geometry, normals pointing inside, multiplier 1 - 1.5)
• If you're using many lights raise the light samples to ~12
• Use "fake glass" material for window glass: single plane geometry with chrome material settings but falloff map in opacity slot (ior set to 2)
• GI Clamp: a crucial factor in lowering render times. Try 0.2 and compensate with exposure/burn value
• Set "noise threshold: to 0.02 and "min samples" to 0.1
• Try switching on/off "direct light" (importance sampling) in environment and compare render times/look
• Switch off "low priority" in the gpu manager
• On the hardware side you're hopelessly underpowered

[selim alp yumlu]

actulay u can optimize ur noise level as u wish .just wacth this tutor. https://www.youtube.com/watch?v=jM6ctQQENYs.