Black Sclera in the eyes.

Model is Gen 8 female.

Rendersettings are mostly defult except for the following

I'm rendering Full HD 1080,

minsamples =100,

Max samples =1500,

max time (secs) =295200,

Instance Optimization =Speed,

irefly filter =Enabled, 

 

My render cooked for 2 hours.

 

EyesExample.jpg
1056 x 1080 - 976K

Comments

  • ChoholeChohole Posts: 33,604

    Did you centre the model

    this has been mentioned before in others of your threads.

     

    The other solution is to parent everything to a null and move the null until your model is in the center of the grid.

     


     

  • MidyinMidyin Posts: 221
    edited March 2020

    null?(nevermind, I just googled what a null is.)

    Post edited by Richard Haseltine on
  • jim_doriajim_doria Posts: 82

    Funny, I'm just now having the same issue. What does centering the model have to do with it? You mean positioning the model closer to the world origin?

     

  • ChoholeChohole Posts: 33,604
    edited March 2020
    jim_doria said:

    Funny, I'm just now having the same issue. What does centering the model have to do with it? You mean positioning the model closer to the world origin?

     

    From my previous post


    The other solution is to parent everything to a null and move the null until your model is in the center of the grid.

    Post edited by Chohole on
  • jim_doriajim_doria Posts: 82

    OK, I tried moving the figure closer to 0,0,0 and both texture issues I was seeing (black sclera & black patches on the scalp) are gone! 

    Seems weird that the positioning of the model affects the rendering of the textures. Is this some known bug in DAZ Studio?  In Iray? In G8? A G3 character at about the same place has none of these issues.

    I created this large set and I wanted to put characters in different places. Do I have to reposition the set each time to keep the characters closer to the origin?

    Does anyone know the thresholds? Can the model be at 100,100,100? 500,500,500?

  • LeanaLeana Posts: 9,682
    edited March 2020

    It's a problem with Iray dealing with surfaces very close to each other, like the cornea and eye, when they're far from origin.
    From what I've understood, the problem comes from the fact that Iray uses a numeric format which allows a fixed number of digits to represent positions.

    When something is close to origin, it doesn't use many digits for the "main" part of the number (before the digital point), so there are plenty of digits left for decimals and it can be very precise.

    When something is far away, it uses more digits for the "main" part and doesn't have much left for decimals. So rounding can lead to surfaces very close to each other being considered as overlapping, thus creating render artifacts.

    Morphing the cornea a bit farther away from the eye can sometimes help with the problem.

    Post edited by Leana on
  • codex34_f5f1fb6f55codex34_f5f1fb6f55 Posts: 148
    edited March 2020
    jim_doria said:
     

    Does anyone know the thresholds? Can the model be at 100,100,100? 500,500,500?

    Yes, the grid is basically the extents. (it's a box +/-2048 in the x direction, +/-4096 in the z direction, +/-4096 in the y direction) The grid is +/-2048 and less confusing.

    However if the iray instancing optimization is set to memory, this is reduced (on my machine) to +/- 256.

    The reason is because the eye is made with 2 layers, the outer (reflection/refraction) layer is 0.1 units from the inner (sclera/iris) layer.

    The trigonometry required for 3D, such as dot products, needs to allow accuracy for numbers much higher than you give it, so in reality you need to use smaller modelling extents than the numbers will allow just so your calculations don't loose accuracy. 32 bit Floating points can only handle numbers with 7 figures ie 12345.67 so you can represent the next number correctly ie 12345.68 but not 12345.675

    It is what it is.

     

    Post edited by codex34_f5f1fb6f55 on
  • This is the same issue as in yoru previous thread, in which the solution of moving things so the section you are focussed on is in the middle of the world was mentioned https://www.daz3d.com/forums/discussion/391186/weird-problem-with-hair-brows-n-anatomical-elements#latest

This discussion has been closed.