Tiny white pixels on and around eyes for G3F

Triaxe

Hello.
I seem to have a particular issue with Genesis 3 materials. I'm using DigitalTouch's Yolanda and Catherine in particular.
I noticed that in DS 4.20 that no matter what lighting I try, I'm always getting these tiny white specks of dust. The eyes in particular have it really bad but it's pretty much everywhere on the skin. It's just more noticable on the eyes for whatever reason. All of it is Iray. I added a picture to illustrate the problem.

I don't have this issue at all with Genesis 8 materials which my GPU (RTX 3080) renders quickly and without any visual problems. Why are G3F so problematic to render? Does anyone know if I can fix this? I'm currently gutted because having these G3F materials/models bugged like this for me means I won't use them even though I adore the look of them. If anyone can provide assistance I would immensely appreciate it.

 

 

 

 

 

 

Richard Haseltine

There is still noise in the eyes - Iray works by progressively refining the colour values of each pixel through repeated iterations, and one of the default stop conidions is hitting a specific proportion (95% by default) counted as done. Some eye materials take a long tiem to converge, and so they may account for most of the remaining 5% of unconverged pixels 9and may be a long way from converged too).

Possible workarounds, all of which will take time:

• Increase the target Convergence Ratio in render Settings - setting this so it includes the eyes, at least in part, should ensure that the whole eye area is at least close to "done"
• Increase the Render Quality, also in Render Settings - this makes Iray fussier about what it calls done, demanding a more stable value from the 95% 9or whatever) of pixels that must be converged may give the eye area time to get close enough.
• Switch to the Spot Render Tool, in the Tool Settings pane set it to go to a New Window, and drag out a rectangle just enclosing one or both eyes - because the eyes account for a larger proportion of the image area it should keep going until they are done even without adjusting settings. Save as PNG or Tiff and you should get the sharp eyes as a floasting layer that you can drop on top of the main render.

Triaxe

My settings are pretty much the same across the board, I've tinkered with those settings you mentioned but couldn't come to a satisfying result.

What I don't understand is why do the same eyes render perfectly fine on a different model with G8F mats? If, for example, I apply the Yolanda or Catherine mats to a model, then change the eyes then the issues I described persist. Yet when using different mats (same artist, just G8F mats), then switch to the same eyes, they render perfectly fine. What's also curious to me is that the G3F mats go absolute haywire at the start which is not what happens for the G8F mats. One is bombarded with white pixels (shown in the first picture), the G8F one is just pretty much a clear image instantly.

Added some pictures to further illustrate what's happening.

 

 

 

Triaxe

After experimenting for some time, I've managed to find a solution to attain a satisfying result.
The main culprit for me was the 'Share Glossy Inputs' setting, most notably when it was turned on for EyeMoisture and Cornea. I set it to 'Off' for these two properties, along with other properties where I felt the area was problematic (face in my case too). In addition, I set 'Metallic Flakes Weight' to 0 .

This works adequately for everything except maybe the eyes still. I noticed that I still had just a few minor pixels in and around the pupils. Since the area surrounding the eyes didn't show any pixels (or at least not enough for me to notice) I got lazy this time and just copy/pasted the eye surfaces from another character. I'm sure with more time and tenacity I could probably figure out which settings exactly caused those few minor pixels to remain but I'm happy with the result for now.

Hope it helps someone else with similar issues!

Richard Haseltine

I suspect that changing the mats in this case is changing only the base colour map, not modifying the settings, and its the detailed settings - especially things like reflection,refraction, and scattering - that slow the process down (because they are much more senstive to the angle of the incomong light path).