Glas reflection turns black?

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Old 08 August 2013   #1
Glas reflection turns black?

Hi guys!

Im trying to get my liquid and glass to collaborate with me. I really don't know why the bottom part, which is in chrome/silver, reflects black as soon as I add the glass and liquid?

I've been messing around with the settings on the liquid, glass and the bottom part with no luck. My first thought was that the bottom chrome part not was two sided, but as you can see both the inner and outer part of the bottom is in chrome.

Is there any common mistakes when dealing with glass and liquid?

(Left image with all applied, right with glass and liquid hidden)

 
Old 08 August 2013   #2
What renderer are you using?

Try increasing the reflection depth.
 
Old 08 August 2013   #3
Depending on what material you're using you may need caustics for the light to go through the glass
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Old 08 August 2013   #4
Im using Keyshot 4 but tried Vray aswell with the same result. In Keyshot Im using a liquid and glass material preset. In Vray aswell, from the "Vray Material Presets Pro". So I haven't come up with my own preset.

I tried increase the depth without no diffrence.

Edit: Mixing with the IOR setting by decreasing its value helps a bit, but still not good. Increasing the IOR makes the bottom of the liquid look like a thick bottle... Hmm.

Last edited by Bondra : 08 August 2013 at 06:53 PM.
 
Old 08 August 2013   #5
are your normals ok?
are there any faces overlapping?

could you upload the problematic part of the scene? that way we can have a closer look at it.

Last edited by CHRiTTeR : 08 August 2013 at 08:07 PM.
 
Old 08 August 2013   #6
Im not a experienced user, can you please explain normals?

I don't think there's any overlapping in my model. I made a test making a cylinder with round bottom and there are some wierd dark areas (at the top) in that one too (see right model).

Have a look at the image, isn't it a wierd reflection? The model right next to it gets black? When it's actually transparent?



Originally Posted by CHRiTTeR: are your normals ok?
are there any faces overlapping?
 
Old 08 August 2013   #7
Does your glass have thickness? It looks to me like it doesn't, if not then you need to use something like the Shell modifier.
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Old 08 August 2013   #8
Originally Posted by Bondra: Im not a experienced user, can you please explain normals?


In short:
When a 3D object is made out of flat faces/polygons... The normals tells the software which way these faces/polygons are facing.

When your normals are facing the wrong direction it can give weird/unwanted results (especially with refractive materials).

The strange noise in your renders might be the result of overlapping faces though...

Is this an imported model?
 
Old 08 August 2013   #9
Not at first til you mentioned it. Now it has but still wierd reflections :/

Originally Posted by darthviper107: Does your glass have thickness? It looks to me like it doesn't, if not then you need to use something like the Shell modifier.
 
Old 08 August 2013   #10
Thanks for your respond!

No it's not imported. I have modeled it. I used the lathe modifier. And start thinking that something maybe went wrong at that part of the modeling process?

The noisy image is caused by being too quick on the printscreen. It's the active shade live render. I didn't give it enough time to render to a better quality. The result though, with the dark shadows is the same in the actual render.

Originally Posted by CHRiTTeR: In short:
When a 3D object is made out of flat faces/polygons... The normals tells the software which way these faces/polygons are facing.

When your normals are facing the wrong direction it can give weird/unwanted results (especially with refractive materials).

The strange noise in your renders might be the result of overlapping faces though...

Is this an imported model?
 
Old 08 August 2013   #11
There's truly something freaky going on. When the liquid object intersect with the glas object it gets totally dark!

Jesus christ, what's wrong!



Originally Posted by Bondra: Thanks for your respond!

No it's not imported. I have modeled it. I used the lathe modifier. And start thinking that something maybe went wrong at that part of the modeling process?

The noisy image is caused by being too quick on the printscreen. It's the active shade live render. I didn't give it enough time to render to a better quality. The result though, with the dark shadows is the same in the actual render.
 
Old 08 August 2013   #12
If you upload the scene, as chritter mentioned, we could take a look at it.
 
Old 08 August 2013   #13
Here's the scene. The liquid in the bottle is suddenly black and I have no clue what's going on.

The scene

Originally Posted by musashidan: If you upload the scene, as chritter mentioned, we could take a look at it.
 
Old 08 August 2013   #14
Your liquid geometry is a shell mesh, whereas it should be solid. Your scene is also not setup correctly for physical accuracy. No Vray cam. You are not using a linear workflow either. This is important if you want to get accurate renders.

Also, on the point of the black chrome reflections, refracting through both the glass and the liquid: this is physically accurate. The reflection is influenced by the colour of the chrome surface(black) as it is refracted through the glass and liquid. As a test, apply a vray material with no reflective properties to the chrome surface. Now change the diffuse to different colours(bright red/green/blue) and you will see what I mean.

And as a real-world example: find a perfume(or any) bottle in your house with liquid in it and hold different objects behind it. Observe how the reflected refraction behaves.
 
Old 08 August 2013   #15
Thanks for your reply!

With solid, do you mean that I should not have applied any shell to it at all? Instead have a thin surface were each polygon was sharing front and back? (If that's the case, this was how it was made from the beginning, still with reflection problems though)

Is a cam necessary from the beginning? I mean, there will be a diffrence depending on if I look at a bottle with my eyes and through a camera? Isn't the view from the beginning kind of "natural"?

Please explain more in detail, what is a linear workflow?

I have the bottle which I've modeled in front of me. The bottom part is pretty clear despite light or dark surrounding. I tried to place the bottle in front of a black background, and the only part that was bright in poor light was the liquid which reflected the bright chrome part.

That's a bit wierd since the behavior in 3Ds is the opposite.

Thanks for your time guys!

Originally Posted by musashidan: Your liquid geometry is a shell mesh, whereas it should be solid. Your scene is also not setup correctly for physical accuracy. No Vray cam. You are not using a linear workflow either. This is important if you want to get accurate renders.

Also, on the point of the black chrome reflections, refracting through both the glass and the liquid: this is physically accurate. The reflection is influenced by the colour of the chrome surface(black) as it is refracted through the glass and liquid. As a test, apply a vray material with no reflective properties to the chrome surface. Now change the diffuse to different colours(bright red/green/blue) and you will see what I mean.

And as a real-world example: find a perfume(or any) bottle in your house with liquid in it and hold different objects behind it. Observe how the reflected refraction behaves.
 
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