The Optix imager can denoise the beauty and any other AOV.
The so-called layer selection tells the imager what AOVs to denoise. For example, if you want to denoise both the beauty and the coat AOVs, enter RGBA or coat in the Layer Selection text box.
Using AOV names with or is an easy way to select multiple AOVs.
You can also use wildcard characters (such as *, ., and []) to select AOVs (this is what is called glob in the docs). For example:
*
Selects all AOVs
RGBA_*
Selects all light group AOVs for the beauty (for example, RGBA_default, RGBA_key, and so on)
RGBA_light0[135]
Selects RGBA_light01, RGBA_light03, and RGBA_light05
RGBA_light0.
The period (.) matches any single character, so this selects RGBA_light00 through to RGBA_light09. RGBA_light0[1-9] does the same thing.
You can even use regular expressions for more complicated selections. But in general, using or and wildcards should be more than enough.
The AOVs and variance AOVs are in separate EXRs That’s necessary to be able to have different filters for the same AOV in MAXtoA
Tip: In the Windows command prompt, you can use ^ (Shift + 6) character to indicate line continuation, and break long commands into multiple lines. You can also use ^ in in a batch file.
Here’s how to use the 3ds Max object ids for a simple Object ID AOV.
And here’s the material (aka shader tree) that writes the AOV. Use a text editor to save this as Arnold Scene Source (.ass) file, and then import it into 3ds Max (like I did in the video).
An ASS file is a plain-text file.
### exported: Thu May 21 07:53:19 2020
### from: Arnold 6.0.3.0 [991b08e9] windows icc-17.0.2 oiio-2.2.1 osl-1.11.0 vdb-4.0.0 clm-1.1.1.118 rlm-12.4.2 optix-6.7.0 2020/04/17 09:11:12
### host app: MAXtoA 4.0.4.36 (2021) 3ds Max 23.0.915.2021
aov_write_rgb
{
name /Write_Object_ID_AOV
aov_input /gBufID_Switch
aov_name "object_id"
declare nodeName constant STRING
nodeName "Material #43"
}
switch_rgba
{
name /gBufID_Switch
index /gBufID
input1 1 0 0 1
input2 0 1 0 1
input3 0 0 1 1
}
user_data_int
{
name /gBufID
attribute "gBufID"
}
This is actually pretty cool…you can use an operator to update file paths before an ASS file or ABC file is loaded, then use another operator to touch the geometry loaded by that procedural.
For example, suppose at render time you want to replace trex_proxy.abc with trex.abc. You can easily do that with a string replace operator:
*.(@node==’alembic’) selects all Alembic procedural nodes
Match matches any file name that ends with “_proxy.abc”
Replace replaces “_proxy.abc” with “.abc”
And that all happens before the abc file is loaded.
We can see this in the Arnold log (Debug verbosity). First the string replace operator is applied; then after the abc file is loaded, a set parameter operator is applied to the nodes loaded from the abc file.
Controllable auto-instancing on ASS procedurals: You can now disable the default automatic instantiation of procedurals pointing at the same ASS file with the auto_instancing parameter on each procedural or by the procedural_auto_instancing option. This workaround is sometimes useful when overriding procedural parameters with operators.
It means that if you load the same ass file many times, Arnold will load the ass file just one time, and then automatically create instances of that. For example, if I load an ass file three times, I will get two instances.
In previous versions, this was known as the procedural cache, and it was a global option. Now it’s called auto_instancing and you can set it on each procedural node (aka aiStandin in Maya).
In general, you want auto instancing, because instancing is more efficient than loading the same ass file over and over. But if you’re using operators to apply different looks to the same procedural, you need to turn off auto instancing. Otherwise all the procedurals will have the same look (because they all be instances of the same one procedural).
For example, with auto instancing on, I get this, even though I’ve assigned different looks to each procedural (standin):
Everything has the same look with auto instancing on
I can also tell from the Arnold log that I’m getting instances. Note that 2 are reused
| ---------------------------------------------------------
| ass file cache
| unique (loaded from disk) 1 (33.33%)
| reused (found in cache) 2 (66.67%)
| total referenced .ass files 3 (100.00%)
| ---------------------------------------------------------
If I turn off auto instancing (in the procedural parameters)
then I get three different looks
In the Arnold log, that looks like this (0 reused means 0 instances)
| ---------------------------------------------------------
| ass file cache
| unique (loaded from disk) 1 (100.00%)
| reused (found in cache) 0 (0.00%)
| total referenced .ass files 1 (100.00%)
| ---------------------------------------------------------
Arnold 6.0.2 includes a new string_replace that lets you do find and replace on string parameters.
For example, I got an ass procedural file from a user, but I didn’t get the textures. Normally I would just enable ignore textures, but this time I used string_replace to replace all textures with my trusty-old-Softimage noicon pic.
string_replace operator in MtoA (Maya)
Selection selects all Arnold image nodes. So this string replace operation applies to all string parameters of the image node (which includes name, uvset, color_space as well as filename).
Match is a regular expression that matches anything that looks like C:/project/sourceimages/example.tx or X:/temp/test/example.tx
[A-Z] matches any drive letter from A to Z
.* matches any string of characters
Note that match is a regular expression, so you cannot use glob wildcards like this: C:\sourceimages\*.tx (because * is not any string of characters, it is zero or more occurrences of the previous character)
\.tx matches a period followed by “tx”. The period has to be escaped with a backslash because ‘.’ matches any single character
Note that this match expression won’t handle something like example.txtra.tx
Replace is the string that replaces anything matched by the Match expression.
You can use the wireframe shader to drive the opacity of a standard_surface.
The wireframe shader itself doesn’t support opacity, and neither do the flat, utility, and ambient_occlusion shaders. They are all color shaders (RGB). In Arnold, only shaders that return closures can support opacity.
In the more general case, where the opacity isn’t coming from the same shader, you can use the emission for the color:
Arnold Support Corner 