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Shader - Transmission / Refraction in Arnold compared to other render engines

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Nachricht 1 von 9
am_wilkins
954 Aufrufe, 8 Antworten

Shader - Transmission / Refraction in Arnold compared to other render engines

Good day,

 

In some recent render testing, I noticed that with matching (as far as I can see) shader and render settings across different render engines—Arnold appears to be the "odd one out" when it came to a glass shader.

Here are the render examples below.

(some render engines appear to need extra ray-depth, even though they're all set to 3 bounces)

 

Shader setting example:

Base / Diffuse: 0

Spec / Glossiness: 1

Transmission / Refraction: 1

IOR: 1.52



Arnold:


ArnoldArnold

 

Redshift:

 

RedshiftRedshift

 

Karma:

 

Karma XPUKarma XPU

 

Vray:

 

VrayVray

 

Why is the Arnold result so different to all the others?

Any suggestions to get the result matching? I tried increasing IOR even more, but that seems the incorrect choice.

 

 

All the best,

amwilkins

 

 

 

 

8 ANTWORTEN 8
Nachricht 2 von 9
daniel
als Antwort auf: am_wilkins

Could be a ray depth issue?

 

Nachricht 3 von 9
am_wilkins
als Antwort auf: daniel

Hi,

 

No I don't think so—I've got all render engines set to 8 transmission / refraction depth
(Likewise, 3 diffuse and specular bounces)

Some of the engines like Redshift seem to require additional depth then those dark zones go away, but just left same settings for now.

 

Interesting how Karma, Vray and Redshift all look similar and Arnold is so totally different.

 

some setting examples:

ARNOLDARNOLDREDSHIFTREDSHIFT

ARNOLD RAYDEPTHARNOLD RAYDEPTH

 

 

Thanks!

 

amwilkins

Nachricht 4 von 9
daniel
als Antwort auf: am_wilkins

There is your issue, you limit your total ray depth to 10, hence the 8 transmission depth cant kick in.
Nachricht 5 von 9
am_wilkins
als Antwort auf: daniel

Hi Daniel,

 

Unfortunately that's not the issue... I can set "Total" super high but the render result doesn't change.

Attached below, very high depth across all settings (just to rule out any sort of ray depth problems)

arnold_render_settings_01.jpg

 

 

amwilkins

Nachricht 6 von 9
daniel
als Antwort auf: am_wilkins

I guess you would need to export/provide a scene then to rule out any bugs.. if you can export an abc, I can check it in another dcc
Nachricht 7 von 9
am_wilkins
als Antwort auf: daniel

It's just the "Stanford Dragon"
https://casual-effects.com/data/ 

With a Arnold Standard Surface shader using they're own glass preset.

Nachricht 8 von 9
nobody_b
als Antwort auf: am_wilkins

i think you have double sided geo off

Nachricht 9 von 9
am_wilkins
als Antwort auf: nobody_b

Hello,

 

Yes!

That did the trick... I'm using Solaris—for some reason the default behavior for Arnold appears to be different to other render engines.

So I had to drop down a render geometry settings node to correct it.

 

double_sided_settings.jpg

 

Thanks for the help!

 

amwilkins

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