Banding on specular material

[mitchino]

The attached pic shows a problem I'm having with a plastic bottle render - it's a hand cream product.

The model is made using a low poly mesh inside a SDS, the way I always model bottles. There is an overlapping mesh on the inside for the liquid. The liquid has a white glossy material, the bottle has a specular material using an absorption medium fed by an RGB spectrum for colour.

There is banding on the bottle surface and I can't seem to fix it. I have tried:

Playing with the phong tag.
Playing with smooth and far shadows in material common tab.
Playing with ray epsilon and other settings in the Pathtracing kernel settings.
Playing with the SDS settings.

Just can't seem to shift the banding. It's something to do with the absorption material as the banding goes away with a simple specular with a colour in the transmission. However I need to use absorption as the bottle has thicker areas where the colour of the plastic is deeper.

Can anyone suggest a solution?

[bepeg4d]

Hi,
please, disable the c4d SDS object, and apply to it an Octane Object tag, with the same subdivision in the proper tab:

If not enough, please post a screenshot of the Absorption node, or even better an example scene that shows the issue, thanks.

ciao Beppe

[mitchino]

The Octane Object Tag gave the same result.

Screen grab of absorption settings attached

[aoktar]

try base objects without using mix material. Also test your materials on different objects.

BTW, I never advise using mix-materials anymore since we have composite material. It's much better for our workflow.

[mitchino]

Same results if I just have the absorption material on the bottle and not the mix material.

simplified file attached

[bepeg4d]

Hi,
the issue seems in the Plastic bottle topology, if you apply the same material to the Liquid object, everything is smoothed:

ciao Beppe

[mitchino]

Don't understand that - the liquid mesh is just a copy of the inner polys of the plastic bottle mesh, with the normals moved to create an intersection.

[mitchino]

I made the SDS with the low poly model inside editable, then put it back in another SDS, and tat seems to give me a smooth enough result.

[mitchino]

This is not a modelling issue - here is an A/B comparison, on the top the plastic bottle has absorption for colour, on the bottom it has RGB in the transmission slot.

The banding is only visible on the absorption version.

Is there fix or is this a limitation of Octane?

[bepeg4d]

Please try to assign the absorption version on material to a standard cylinder primitive and report back, thanks.

ciao Beppe