Blotchy materials through liquids

[kayekit@gmail.com]

Hi Guys,
I am having real trouble with light and dark patches on a material through a liquid.
Annoyingly i can't post the .Bip file as i am under NDA, however i can post a region render of the issue.

Think of it as a straw in a glass of water and a label stuck on the back of the glass that can be seen through the liquid...


As you can see, the straw (red bit) is covered in light and dark patches and so is the back of the label. I have tried a lot of settings, but i hope someone can help me out. Ideally i'd like to keep the render time to less than an 1.5h as i have to process a lot of angles and label variations.

It also seems that if i put up the Gi to above 2, it just gives me a black render window.. thoughts on that?

The settings are:

Cloudy Plastic : 32 samples
GI bounces : 24
Ray bounces : 60 (set to see if it helps, but nothing really changed)
Caustics is on (has to be)

I have tried a lot of render setting..
the ones for that region render were:

[adamwade]

I struggle with render setting as well, but here is an easy fix to try.  Under the Render Window > Options > Quality: check the Maximum Time button and type in your 1.5 hours or other time limit.  Then render.  This setting allows Keyshot to configure itself to give you the best it can within the set time.  It can solve many things, but it doesn't tell you what it did, so you can't learn from it.

[Will Gibbons]

Hi Kayekit,

This looks to be the effect of caustics. The longer they get to render, the smoother they'll appear. Unfortunately, your hardware and the resolution of the image will ultimately decide how long the image will take to 'smooth out'.

That said, looking at your settings, I have a feeling you can optimize them.

I would try this:

Samples - 32
Ray Bounces - 12 (I'll bet you have this way too high)
Anti Aliasing - 2
Shadow - 2
Global Illumination - 2
Pixel Blur 1.5
DoF - 3 (if you can disable this, it will largely impact the render time)
Caustics - 3 or 4 (this is the thing you're trying to 'smooth out'

Finally, you may find that it helps if you disable 'Global Illumination Cache' but only do it if the above suggestions don't help. This will make it take longer but may improve the image quality.

Good luck. Please post the results here.