Material Bug: rendered as reflective metal

[philippe_grasset]

Hello, this blue material keeps getting rendered as a reflective metal, at random, it may be some geometry issue but seems more like a bug, it get's fixed by reversing face or reapply material, but this methods doesn't always work..what exactly causes this issue?

[konstantin_chaos]

Hi philippe_grasset,

The issue is with the geometry.
There are a couple of issues actually:

1) Some face normals are facing inwards:

The dark gray faces on the left are reversed.
To fix them you have to select the dark faces and use the Reverse Faces context menu option in SketchUp.

2) Some faces have "strange" normals.
This applies to the two boards on the right.
To fix those I tweaked the soften/smooth parameters in the SketchUp's Soften Edges pane:


Here's the result after applying both fixes:


I think it looks correct now.
Let me know if there is anything additional that I've missed.

Regards,
Konstantin

[konstantin_chaos]

Hi philippe_grasset,

Can you please share a simple example scene for us to test?
If that is not possible please share a more detailed description of your material configuration and the situations in which the material changes.

One thing that you can check right away is whether the surface with the problematic material is overlapping another surface with a different material.
Overlapping mesh faces should be avoided in all cases (there is no good way for the render engine to handle those).

Regards,
Konstantin

[philippe_grasset]

Hi Konstantin,

there is no overlapping, if I reverse face the material is semi transparent, reversed metallic reflective, seems to happen randomly. Please check the sk file too.
How can I share the scene , i m not allowed to upload vray scene or sk file? I ve uploded here... is just 10 mb file, https://we.tl/t-BZfcjeRTA0

[fixeighted]

I looked at this in Max, as I do not use Sketchup, and as expected it is pretty messed up geometry, with flipped faces and coplanar faces everywhere, so you would get these errors.

[konstantin_chaos]

Hi philippe_grasset,

The issue is with the geometry.
There are a couple of issues actually:

1) Some face normals are facing inwards:

The dark gray faces on the left are reversed.
To fix them you have to select the dark faces and use the Reverse Faces context menu option in SketchUp.

2) Some faces have "strange" normals.
This applies to the two boards on the right.
To fix those I tweaked the soften/smooth parameters in the SketchUp's Soften Edges pane:


Here's the result after applying both fixes:


I think it looks correct now.
Let me know if there is anything additional that I've missed.

Regards,
Konstantin

[philippe_grasset]

ok, thanks Konstantin I ll try tweaking the soften/smooth parameters if that happens again