[DAZ] render quality issues, hole-pixels, weird hair shadow

[f95zoneuser463]

I frequently encounter these two problem with DAZ Studio that I cannot explain and/or solve in a way that is acceptable.

1. HOLE PIXELS:
-random transparent pixels
-only seem to appear on characters skins
-these are not fireflies, yes I am damn sure!
-appears more frequently the longer a image was rendered
-some scenes never have this, others always

2. WEIRD HAIR SHADOWS:
-seems to happen in low light scenes, sample image is exposure=8
-shadow looks extremely grainy no matter how long you render, sample image is 63000+ iterations.
-I'm not sure whether this is a shadow at all since it leaves a hard line on the face.

Sometimes I get concerned that my GPU is about to rip because of these artifacts/glitches, but doing some test with the CPU revealed that this is not the case.

Any ideas how to avoid these things? Anyone had similar problems?

 

[Rich]

Hard shadow artifacts are sometimes the result of using "point lights". (i.e. spotlights that are configured to be a "point" rather than a rectangle. (And "point" is the default when you create a Daz spotlight, so this is an easy mistake.)

No real light has an infinitesimal area. The finite area of a real light softens ever so slightly the edges of the shadows it generates, and means that light will "make it past" small items like hair strands.

A Daz point spotlight, however, will cast a perfectly hard edge, which can lead to odd-looking lighting artifacts, such as a single strand of hair casting a shadow that would otherwise not be visible.

So that's what I'd check for your second issue. I have no idea about your "transparent pixels," but if it's happen systematically, it's almost certainly not your GPU...

 

[f95zoneuser463]

Unfortunately that's not it. The only light-source in the scene is the daylight from the dome. No other lights or emissive surfaces.

The only thing I know for sure is that it's coming from the hair. Removing the hair does fix it. The scene is indoor and light has to travel through windows. It's slow rendering/indirect light this way but realistic. I can't change much or the light will no longer match with already finished renders. The really annoying thing is the time needed to check whether it was fixed after changing something. It's only visible after many iterations.
For now I fixed it in the post with the healing-tool in gimp ... but that's just a very bad and very ugly workaround.

Anyway, thanks for helping Rich.

EDIT:
1) Hole Pixels seems to be related to

You must be registered to see the links

. G8x characters with shaders using Dual Lobe + SSS.