Please Critique my render.

[Dustin Zalesky]

i’m having some issues with the liquid creating some weird triangles of darkness, i’ve experimented with changing all kinds of reflection/refraction settings but it won’t go away… the only way to get rid of it is to reduce the size of the liquid all the way past the plastic bottle… from what I’ve read the liquid needs to be in-between the thickness of the plastic, and thats how i did it. I took the inside thickness and deleted the outside, then expanded it a small amount so that it sits in-between… am i doing something wrong? here is a screenshot…

[Adam Trachtenberg]

I’ll throw my two cents in with Brian’s suggestions:

1. The biggest time killer in your scene is blurry reflections, which are always slow but doubly so with GI. I used an enviro map on the shelves in place of the reflection and reduced render times from over 15 minutes to under five minutes.

Of course you lose that bit of realism. What you might try is rendering straight reflections with an object buffer for the shelves and blurring the reflection in post.

2. Area lights are another bottleneck. I replaced the long, skinny area lights with an array of 18 omni lights and that knocked another minute of the render time. That didn’t have much effect on render quality (takes some tweaking).

3. Like Brian, I reduced the GI to the low settings, which seems fine for everything but the ceiling, where there are artifacts from the luminous bulb material. To resolve that I gave the light geometry a compositing tag and checked the QMC box in the GI tab. That gets rid of all artifacts but is a little grainy at default. Looked okay to me, though.

Final result: 1:30 render time (having also set AA to animation and lowered the floor reflection samples a bit).

I’m using R13, so unfortunately I can’t provide the file.

[Dustin Zalesky]

Thanks! you guys are giving amazing feedback. I appreciate the help.

[Adam Trachtenberg]

Sounds like you’re doing it the right way. Hard to say what’s wrong without the file.

[Brian Jones]

yes, typically the liquid can’t be in the exact same space as the inner glass layer or you get artifacts, either it has to be ‘in the glass’ like you said or there has to be a tiny space between the liquid and glass. However, your image kind of looks like it might be doing the right thing since it looks like it’s refracting the black background (or maybe that’s just faking me out)

[Dustin Zalesky]

4322_2l.zip

here is the file, i tried putting in a solid white background and no floor and still got the weird black areas… it’s confusing… only way to get rid of them is to shrink it way past the inner plastic.

[Dustin Zalesky]

Here is another render with a white background and the liquid shrunk quite a bit…. if i shrink it any further it looks crazy… do you guys have any idea why it’s reacting like this?

I’ve tweaked a ton of things and couldn’t get rid of it for life of me… I’m try to exhaust all kinds of ideas before i even come here and ask.

[Adam Trachtenberg]

The problem is being caused by GI (it’s renders fine without it). I can’t remember if the option is there in 11.5, but in R13 the GI tab of the compositing tag contains an “Enable Transparency Overlook” option. If I check that box for the liquid object the problem goes away.

Here’s what the help file says about it:

“For transparent objects, the GI Irradiance Cache is not interpolated to bordering surfaces (see also Enable Interpolation Grouping) and is calculated differently from “normal” objects. This makes sense in most cases and is also intentional. In certain instances this can, however, lead to unwanted side-effects. For example, visible errors can result on bordering surfaces of partially transparent and opaque objects (see image above).

This option can also be applied to objects that have a texture loaded into the Transparency channel.

Disabling the Enable Transparency Overlook option will result in transparent objects being treated like any other object with regard to GI.”

[Dustin Zalesky]

Thanks!!! you’re very helpful as always.

Btw i don’t think that option is available in 11.5… man i need r13 😉 maybe i can talk my company into upgrading (doubtful)

[Brian Jones]

good one Adam, thanks. Dustin if you disable Total Internal Reflection and Exit Reflections on the liquid and bottle materials (transparency tab) the render is a *lot* quicker (if it doesn’t spoil the look)