Translucency: orange juice in glass

[flipside]

Hi,

Here's something that bothers me already for a long time. Whenever I want to render orange juice, I have this problem, also in vray for max.

I draw a glass and liquid in it. When I render the liquid with orange juice material (translucent), I get this:


Then I unhide the glass, and I get this:
(Here I modeled the liquid slightly larger than the inner glass surface.)



When I remove the inner glass surface, and render, I get this:



Why is the glass blocking so much light? I cannot believe that orange juice will get so much darker if I poor it into a glass, than as if it were floating around in the air.

I understand that because of reflection, a portion of the light is bounced off from the glass, but this darkening of the juice seems a bit extreme.

[vlado]

Translucency: orange juice in glass

Can you show the glass material? Does it have the "Affect shadows" option on? Also, what is your reflection/refraction raytrace depth?

Best regards,
Vlado

[flipside]

Translucency: orange juice in glass

The glass material has affect shadows turned on, otherwise it is relying on GI caustics which makes it way more difficult (blotchy). The juice material also hase this turned on, that makes the light transport a bit better it seems.

Max depth is 12, I tried 30 too, which didn't help. The glass is a very standard glass setup. Black diffuse, white reflection and refraction, fresnell turned on, both ior=1.55. Reflect on backside is turned on.

Here's a new test:



Is there a small summary of what each setting in refraction represents when using translucency? I can always create the same look with 10 different combo's of settings, but they all react to varying light situations differently of course. I really don't know what I'm doing, it's always trial and error.

For example the difference between dark fog with low multiplier, or light fog with higher multiplier. I usually end up using greyscale only for refraction, and white for translucency color, otherwise you have four interacting colors (diffuse, refract, fog and translucency) instead of only two (diffuse and fog).

[flipside]

Translucency: orange juice in glass

Continued the testing. Here are some maybe interesting results. Maybe the vray surface interaction doesn't work well with translucency? I remember something about vray being able to render liquids in glass if you model the liquid slightly bigger, which is not in every renderer out there. But here it seems to introduce problems.

Please Vlado take a look a this, before I go completely crazy, I think I've done already a thousand test renders of the same scene... I cannot post the scene, so if you want I can mail it to you.

With skylight only, everything works better, the problem isn't that noticable then.

Liquid smaller than inner glass surface:



Liquid a bit bigger than inner glass surface:



Inner glass surface removed:

[vlado]

Translucency: orange juice in glass

Yes, the scene would be handy for testing, thanks in advance.

Best regards,
Vlado