Problem with rendering of a faceted glass in Cycles

Hello. I have a problem with a faceted glass in Cycles render and I can’t solve it.

  1. The main issue that I can’t solve - glass of the top lid has some artefacts on the sides and whatever I do, it doesn’t help. (P.S. Yes, increasing values of light paths (max bounces) I did. It’s not work for this case)
    2.There is also the problem with glass and liquid, I made a surface tension, and overlapping of glass and the liquid, but it does not look realistic. How to fix it?
    Here is link to this 3d model with HDRI for clarity. Thanks for the help.

Welcome to the community!

1- Are you sure those are artifacts? They look like the actual correct reflections to me. The metallic part is reflecting the inside of the glass lid and some angles create rays that bounce inside the glass a large number of times. If you don’t want these reflections, just change the material of the metal part that’s inside the glass (either make it rougher or non-metallic).

2- If you want full realism, then you need to represent the transition between liquid and glass using a single surface, with a different glass material just for that section of the container. The inside of the container would be sliced in 2 different sections in the exact spot the liquid touches the wall. The area below the liquid has a copy of the glass material, but with a different index of refraction (a light ray going from glass to water has an ior of around 1.1).

An other thing: liquids never have a colored surface. Remove the surface color from the liquid object and instead, do the color by plugging a principled volume node in the volume slot of the material. You may have to increase the volume bounces, or else it will look too dark.


I realise my explanation might be hard to understand, so here is an exemple scene. I have made the different materials into separate objects. Pay attention to the normals directions and IOR on each part and how I color the glass shaders with volumes.

realistic_wine_glass.blend (1.6 MB)

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Thanks a lot!!! That’s what I was looking for) I agree, real example is more understandable)

But what about these strange refractions? On top of glass. Is that how it should be?

Great!!! Excelent article!!! Thanks)

But in real life an inside cap has metalic coating. Thanks for the answer about glass/liquid. About a faceted glass, Octane render can solve the problem?

That’s hard to say, we would need to have an identical glass in real life to really compare. Maybe it looks weird because I made the glass walls really thick compared with most real life glasses.

I don’t know if the renderer will make much of a difference here. Unless there is something weird happening with Cycles’ reflections, the rays should follow the same paths in any renderer. I think it has something to do with either the models, materials or lighting. I have some ideas still.

In your photo, I notice the metal material under the lid has a little bit of roughness, but It doesn’t in your 3D scene. Try setting the metal to 0.2 or 0.3 roughness. Right now, you get perfectly sharp reflections bouncing back into each other in a loop, that’s not realistic.

Also, the glass could use a little bit of roughness too, it looks like something around 0.05 to 0.1 in the photo.

Then, you could try change the IOR on the lid’s material. Different materials have different values. Maybe your lid in real life has a different IOR from what you set in Blender, which would make the refractions look different.

The HDR background you use is going to be important too. Even if you have the object in real life, it’s hard to evaluate if the 3D model is correct if the HDRI is different from your real surroundings.

You could add a little bit of volume to the lid’s material. Long rays that bounce recursively inside the material would progressively darken and fade to the color of the glass/plastic.

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check your normal and dup verts

auto smooth and only mark outside facets sharp

Hi. Really if add a bit of roughness, the result’s getting better. BUT main problem with render engine Cycle. Here are 2 renders. 1 - Octane , 2- Cycles

Let’s review the differences.

It looks like the octane material has transmission roughness and the Cycles version doesn’t. In your Cycles scene, set the lid material to GGX: this will add the option for transmission roughness (rays will get blurred the deeper they go inside the glass). A value of 0.1 will get you something a bit more similar to the Octane version.

The Octane version has dispersion. This isn’t something Cycles can do right now, so Octane clearly has the more realistic shader on that aspect.

It looks like Cycles is creating more reflections in the metal. Are the bounces set as high in Octane as they are in Cycles? If they are, that could mean there are actual differences in the way the 2 renderers treat materials. You would have to ask someone who about how they are coded to know for sure. Or the differences could just be different color gradings or the position of the HDRI, it’s hard to tell for sure.

Hi, here is maximum what I can make with cycles. I added a roughness and used a fake dispersion in glass material.

But Octane makes better a dispertion. I’d like use Octane, but unfortunately it’s very buggy.

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If you ask me, that’s actually pretty good! Cycles wasn’t designed as the most realistic renderer, but it’s very flexible and allows lots of control, which is great for artistic purposes.

I would be curious to see how other renderers handle the same scene, because I couldn’t say for sure if Octane’s result is fully realistic either.

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Thanks for answers)

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