patches on clear rough plastic

[adidasrinnegan]

Hi all, first poster so excuse my ignorance if i disrupt any rules. Basically having a problem with one of my renders where I am applying the clear rough plastic material to the exterior of a bag that has a clear water filled texture with an added blue colour. The issue im having is that the plastic bag displays these patches that i cant seem to get rid of. Tried messing around with the water and plastic caustics and other but no result.

Images attached, all help appreciated. 

[TpwUK]

Scale you liquid down by a fraction .01 for example, you have two surfaces fighting for the same space

Martin

[mattjgerard]

Haha! Same thing I posted on their question on the reddit forum.

[DMerz III]

Another way to solve this would be to use the 'inner surface' of the plastic pod as a separate part, which you would make your liquid, let the outter surface be defined as your clear plastic pod. That way there's not an 'air pocket' between the liquid and the plastic.

[LayC42]

Another way to solve this would be to use the 'inner surface' of the plastic pod as a separate part, which you would make your liquid, let the outter surface be defined as your clear plastic pod. That way there's not an 'air pocket' between the liquid and the plastic.

I do not agree with this. 'Cause there should be no overlapping meshes nor gap between two parts. Just like in the same case of liquid to glass or liquid to ice you need to use different materials. The rough plastic for the outside surfs and a dialetric for the plastic/liquid. Take care of the correct IOR  (refractionindex).
Maybe this link could be helpful?
https://www.keyshot.com/forum/index.php?topic=14200.msg72541#msg72541

Cheers

[DMerz III]

Sorry LayC42, that's what I meant, but didn't describe properly. I meant taking the inner surface of what is already the pod and having it split so you can make it a separate part. (and removing the mesh for the current liquid part altogether). The link you reference explained it way better!

[LayC42]

There is a great webinar from Richard Funell describing this topic
https://youtu.be/HlxF9peYod0