Shadow Graininess

Sector Zero

I'm getting a lot of graininess in the shadows on an outdoor render that I would have thought had plenty of light. Which parameters in Environment or Tonemapper Options (or anywhere else) can I try to adjust to eliminate the problem?

Richard Haseltine

How is the scene being lit?

Cenobite

Sometimes you can turn the headlamp off  if your using that & you'll lose the firefly, if the scene has fog particals some light doesn't interact well with it giving it an unrendered look when a headlamp hits it.

Sector Zero

Cenobite said:

Sometimes you can turn the headlamp off  if your using that & you'll lose the firefly, if the scene has fog particals some light doesn't interact well with it giving it an unrendered look when a headlamp hits it.

Headlamp is turned off in preferences.

Richard Haseltine said:

How is the scene being lit?

I'm using https://www.daz3d.com/parkway--complete-hdri-environment and it's always worked well in the past. I'm using Sun & Sky only. DoF is on, all other settings like f-stop, shutter speed, ISO are all at default. It's definitely graininess, I've had fireflies and have found ways to get rid of them somewhat successfully. I found a post from 2016 that gave some "absurdly high" settings for max/min samples, quality, convergence, etc to deal with graininess and they worked pretty well. The upside is that my video card doesn't react they're absurd, the downside is I'd like to know how to adjust settings so I don't need to clobber the problem with high settings. Along the way I did try changing the f-stop, etc but those results were disappointing, to say the least. Either too dark or white was too blown out, I couldn't find a combination that worked better than the defaults. So, any tips for setting it up better would be most welcome, but either way I've found an acceptable solution.

Richard Haseltine

If you are using Sun & Sky then you aren't using Parkway as it is a set of HDRI environment maps, which requires one of the Dome settings.

margrave

sectorzeromedia said:

I'm using https://www.daz3d.com/parkway--complete-hdri-environment and it's always worked well in the past. I'm using Sun & Sky only. DoF is on, all other settings like f-stop, shutter speed, ISO are all at default. It's definitely graininess, I've had fireflies and have found ways to get rid of them somewhat successfully. I found a post from 2016 that gave some "absurdly high" settings for max/min samples, quality, convergence, etc to deal with graininess and they worked pretty well. The upside is that my video card doesn't react they're absurd, the downside is I'd like to know how to adjust settings so I don't need to clobber the problem with high settings. Along the way I did try changing the f-stop, etc but those results were disappointing, to say the least. Either too dark or white was too blown out, I couldn't find a combination that worked better than the defaults. So, any tips for setting it up better would be most welcome, but either way I've found an acceptable solution.

The optimal settings depend on which HDRI from that pack you're using.

First of all, set the "cm^2 Factor" in the Tonemapper to 10.0. For whatever reason, real-world values in Iray are calculated at a tenth of their actual value, so you need to use that to shift them up to the proper range.

If you're using the HDRI with the clear blue skies, then an f-stop of 16.0 is fine. Shutter speed and ISO can be left at default, because they're pre-set for the Sunny 16 rule. If you're using one of the forested HDRIs, where the sky isn't as bright, you might need to bring your f-stop down to 11.0, 8.0, or even 5.6, depending on how the PA has color graded the HDRI.

Finally, go into your Progressive Rendering tab and turn off Rendering Quality Enable, then crank the Max Samples and Max Time as far as they'll go.

Then hit Render and let it go until the noise is gone.

If it's still too noisy, add a very dim spherical point light or two to the noisy areas to give Iray some more light rays to work with.

EDIT:

Setting "cm^2 Factor" to 10.0 works if you always set your Environment Map down to 1.0, like I do. If you keep it at the default of 2.0, though, you should set your "cm^2 Factor" to 5.0 instead to get the same light level.

Cenobite

I have searched around these environments use the best render settings for day time environments and super quick renders with NO firefly, they are Plains & Mountains, Highlands & Desert environments you can find in DAZ3D store, they are the fastest out of the box renders that enhance all your day time renders for Iray without fussing around with lights, if your doing interior lighting then i suggest creating your own mesh lights & adjusting the shadows according to the light your boradcasting for best lighting effects.

This one rendered in 2 minutes & 20 seconds, default settings and quality, everything i have tested using these scenes render super quick at fairly high detail.