Black Lines appearing on curved surface (bath tub) - how to resolve?

[kristo_crushcov]

Hello, I am trying to render a bathroom project but there are some black lines appearing in the render on the bath tub (see attached images). Does anyone know whats causing it and how to resolve it? Thanks (Vray for Sketchup, latest version)

[natalia.gruzdova]

Hello kristo_crushcov,
Thank you for your post.

You can try to change the material of the bathtub to test if material is causing the issue. If this does not help, most likely there is an issue with the geometry of this particular model. Is it a 3D Warehouse model?

Can you attach the bath here on forum (as .zip archive) or share a link to the original model so we could take a look?

[kristo_crushcov]

Thanks for the reply. I have tried to upload the zip file to this message but it is requiring me to add a URL, how can I do this?

[natalia.gruzdova]

Hi kristo_crushcov,
Are you trying to use Post Link option by any chance? You need to click on the Upload Attachment button, please see the screenshot below:

[kristo_crushcov]

Ok, it seems to be working now!

[DCHA34]

Hi Kristo,
where the problem occurs, there are several faces superimposed on each other.

Problem solved with FixIt 101 extension.

[natalia.gruzdova]

Thank you for the file.

Seems there were some issues with how the Component of that particular part was created. I have exploded and recreated it and it solved the issue. You can see the process in this video.

Also I am attaching the fixed model to this post just in case.

[natalia.gruzdova]

What DCHA34 suggests with the use of Extensions is a good option as well. For example, Clean Up Extension also can be used to fix it: example.

[konstantin_chaos]

Hi everybody,

I just wanted to give you some more general information.
Artifacts similar to the ones in the original post point to overlapping geometry in 99% of cases.

The blackness is caused by self-shadowing of the overlapping faces.
There is something in the V-Ray options that can help called Secondary Ray Bias:



You should consider this option if fixing the geometry is not an option.
In all other cases - fixing the mesh is best.

Konstantin