[jrm1]

I have a scene rendering at the moment which is mostly by emitters (metal halides) and at SL 16 there are still many white dots on some steel items, the material for which has an inox IOR.
I am new to using IORs and I gather they use up a lot of render time. Is this far worse when emitters are the light source or is it just that the noise is noticed more in the picture because the contrast is high when it's just lit with emitters?

Any general warnings or workarounds anyone may have would be great.

[Bubbaloo]

First make sure your scene scale is correct. Then make sure your camera and lights are set to realistic values.

[jrm1]

Not sure what you mean by scene scale - do you mean the size of the emitters should relate to real world light fixtures?
And is it true that very strong emitters would make the rendering of an IOR like inox very long?

[eric nixon]

If you think its the material try rendering on the simball to isolate the problem, if there is noise on the inside of the ring object then the material is too bright.

If the emitters are very small they take longer to render, if you posted a render we could tell you more.

[jrm1]

[jrm1]

The handrail is steel, using inox IOR. The step lights are Metal Halides, approx 40mm diameter. The floor is an Arroway pebble displacement. This is SL 16.5

[Bubbaloo]

Glass or AGS?

[eric nixon]

It looks like the pebbles are causing the noise, and the spotlights shining down onto the pebbles may be a culprit. If the pebbles are an additive mxm that might be it.
Also like bubba says if its real glass it would be good to hide it from GI.

[jrm1]

Thank you Brian and Eric. The glass is simply a Sketchup material with transparency, opacity adjusted in Sketchup until it looks right. So I doubt it's sophisticated.

Ill try taking out the floor, then taking out the down lights and finally the step lights. Maybe also the windows and see what the result/culprit is.

[PA3K]

Hello jrm1,

I think it is displacement material (Arroway pebble displacement - as you note) causing white noise. The noise is only in outside area of the scene and in reflection on the glass and metal parts. Seems only spread by that material. Check displacement properties of that material or just try to turn off it. Personaly I don`t think it is other things...

Patrik