Why does the transparent material have black spots?

Started by gglee7, October 02, 2017, 06:45:26 PM

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gglee7

When transparent materials and paint ground are in contact, black spots are formed.
(It happens even if the height is 0.1mm or 1mm.)
This problem also occurs in keyshot 6.

What should I do?

cjwidd

Ground shadows, Ground illumination, Self-shadows <- have you done test renders with one or more of these settings disabled?
Have you tried disabling global illumination cache?
Are you sure the ground plane is not intersecting the mesh?
Have you tried rendering in interior vs. product mode?

These are just what I would check first. Obviously a mod or a senior member could give you a more exact answer.

gglee7

Quote from: cjwidd on October 02, 2017, 09:44:03 PM
Ground shadows, Ground illumination, Self-shadows <- have you done test renders with one or more of these settings disabled?
Have you tried disabling global illumination cache?
Are you sure the ground plane is not intersecting the mesh?
Have you tried rendering in interior vs. product mode?

These are just what I would check first. Obviously a mod or a senior member could give you a more exact answer.


I have tried various ways to do what your advice.
But I could not solve this problem.
If I turn off the ground shadow function and still see black spots, it does not seem to be a shadow problem.
There is still a problem even if it floats 1mm from the ground. It is not a problem caused by contact with the ground.
I am so tired of this problem. I wonder how I can solve this problem.

TGS808

Have you tried upping samples? 55 is kinda low. Use the region tool to isolate a small area where the problem is occurring, let it res up and see if it goes away. Have the heads up display on while you do this so you can monitor how high the samples were when (if) it goes away. And if it does go away, forget about the advanced render setting and set it for max samples. Set the number of samples to the amount it was at where you saw the problem fixed. No guarantees here but it's worth a try.

Speedster

Be sure to uncheck (disable) "Global Illumination Cache"!  Render > Options, down at the bottom.  I have always gotten black splotches if it's checked.
Bill G