Missing Advanced Render Options in Arnold (Gaffer)

[Matthias Bjarnason]

Hey all,

Looking through some of the more recent features introduced to Arnold renderer, I've spotted a few items in the documentation that I can't seem to locate within Gaffer's 1.5.16.1 (latest Arnold version) Arnold Render Options.

https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_user_guide_ac_render_settings_ac_advanced_settings_html

As seen in Maya here:
https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_for_maya_arnold_am_Advanced___settings_html

I'm mostly interested in experimenting with the Volume interpolation methods here (which is why I went down this rabbit hole in the first place) but wouldn't it make sense to expose all of these in the node, as is done in other packages?

Another fairly recent feature does not seem to be exposed anywhere (not even sure it's exposed in any of the other DCC's) is the "Global Light Sampling (GLS) on glossy materials".

GLS_glossy_enable

See here:
https://help.autodesk.com/view/ARNOL/ENU/?guid=arnold_user_guide_ac_render_settings_ac_lights_settings_html

The light GLS sampling options have been available for some time, which is great, but this related new switch/parameter is nowhere to be found ...at least not exposed in UI.
I'll admit I'm not fully sure if this is a "global" attribute, per object or per light or material ...it's not very clear.

Am I missing something or should these not be available somewhere in Gaffer by default, perhaps they are I'm just not seeing 'em.
Any information appreciated.

Thanks,.
-M

[Murray Stevenson]

Hi Matthias,

Even if we haven't exposed them in the UI, you can usually fall back to setting options with a CustomOptions node. Gaffer will pass "ai:" prefixed options through to Arnold if we're not handling them specifically ourselves, so if you did want to experiment with these, you could add two Bool options named `ai:GLS_glossy_enable` and `ai:stochastic_volume_interpolation` to a CustomOptions node and I would expect them to behave the same as equivalent plugs if they were to exist on an ArnoldOptions node. Arnold's `kick -info options` can list the option names available for a particular Arnold version and provide more information about each option with `kick -info options.<optionName>`.

Both `GLS_glossy_enable` and `stochastic_volume_interpolation` are enabled by default by Arnold, so those options appear to mostly exist to provide a way to revert to the old behaviour, rather than opt-in to the improved sampling and volume rendering speed. As you mention, `GLS_glossy_enable` doesn't seem to be included in the UI of the other DCC bridges, so I don't think we'd be inclined to expose it ourselves, but there may be more of an argument for including `stochastic_volume_interpolation` and some of those other "Advanced" options in the future.

Cheers,

Murray

[Matthias Bjarnason]

Hey Murray,

Thanks for the response.
Yes, although I'm more just experimenting with these at the moment, and can continue to do so using the CustomOptions node,  it was my other thought exactly that there might be an argument made to have these exposed as is in other DCCs ...for easier backwards compatibility  ...for those who are less technically inclined and perhaps not subscribing to the Arnold release notes ;)
...and yes, It's always a possibility Arnold guys remove the "old behavior" completely in future versions so, as you say, it might not be worth adding these in at all (ever) with that in mind.

Cheers,
- M