Eye moisture error black line

amalliach_858df2e8

Hello!

I have a problem that appeared recently. The exact same scene worked fine last month, now, this error on the left doesn t dissappear. 

I tried the "Instancing Optimization to:Speed/Memory", from other threads, but nothing seems to happen. 

The model is a genesis 8.1 and I have an 8.1 skin material on it. What is odd is that if I move the left looking to the left (our right), the black line dissappear. But I need the model to looks straight, not with an eye to the left.

I hope someone can help me solve this....

Thank you!

Willy2

Without knowing where your problem comes from, I will tell you about my following observations.
As I export my Daz scenes to Cinema 4D, I looked at the Genesis 8 eye structure, in order to create appropriate shaders.

This eye structure, for Genesis 8, is quite peculiar.
It is made up of two spheres. The smallest sphere has three zones: the pupil, the iris and the sclera. The largest sphere one that envelops everything includes the cornea and eye moisture.
Even if this representation does not correspond to the anatomical reality of the eye, it is however well designed and allows very good quality renderings.

But, what amazed me is that looking closely at the mesh I had exported to FBX format, is that some of the head polygons are partially inside the eye, this which seems to me to be a design error.
Normally, each eye should be in a cavity totally separate from the head polygons, and should rotate in that cavity, without interfering with the head polygons.

However, despite my criticisms, I am satisfied with the rendering as far as the eyes are concerned.
For your personal problem, it is not impossible that the camera focus will slightly penetrate the head of the Genesis head. As a result, you see spurious polygons.
You should know that in 3D scenes, not everything is allowed. If we approach the camera too close to a mesh, we get anomalies.

NorthOf45

Some character morphs alter the eye shape, but for some reason, the two spheres you mention don't deform equally, so that one actually crosses over into the other, resulting in the black lines at the intersection, probably due to refraction artifacts at very shallow angles. Not to be confused with the black-eyes-at-a-distance problem.

You've probably seen these... What Causes These Black Lines in Eyes?, eyes issues

Willy2

I think the two spheres that make up each eye deform in the same way. Indeed, the vertices of these two spheres are very close together and the faces are of identical size.
Besides, the big sphere which constitutes the cornea and the eye moisture is textured with transparent materials, which avoids this kind of problem.
But this entangling eye and face polygons, as seen in my descriptive image, don't make the render engine's job any easier.
In addition, it is easy to understand why the designer made the polygons of the face fit inside the eye. This avoids having a space between the eye and the skin of the face, which gives a very realistic rendering.
The creation of a cavity (closer to reality) would have introduced a small space, between eye and skin, visible up close.
All of this shows that 3D is a set of compromises. Sometimes we have to move away from anatomical reality to get closer to visual perfection.

NorthOf45

Sorry, that first link got messed up. Check the last comment in that thread, another user confirmed that the meshes crossed. I also verified the effect on another figure that had the same problem (found that comment), eye moisture, apparently, in that case. Zoom in close enough and you can see where they intersect. Yes, they should deform the same way, but apparently they do not always. That needs to be part of the morph controls, but a little out of my depth.