Custom AOV are presented in the AOV Selector's Custom section, and can be selected for output to an image layer just like the built-in AOVs. A custom AOVs is represented by shading nodes of a specific type. The node's name defines the AOV name. The AOV type is defined by the the node, either by an attribute or by the node type itself.
Color and Float Custom AOVs
Color and float custom AOVs values can be defined on a per-surface shader basis. These custom AOV assignments are contained in a AOV Group, which can be used with one or many surface shaders.
Creating a custom color AOV that produces a checker for all objects using this principled shader.
AOV Group
An AOV Group with some custom AOVs.
The AOV Group offers a simple interface to create new AOVs and define value assignments on selected AOVs. An AOV Group can be assigned to a surface shader. All objects that use this surface shader will produce the custom AOV values defined in the AOV Group.
Creating and Assigning AOV Groups
To create and assign a new AOV group to a surface shader, click the checker button for AOV Group in the surface shader's attributes.
Existing AOV Groups can be assigned in the option menu; clicking the arrow button will select the AOV group.
It is also possible to create an AOV Group from the Hypershade's Create panel; it is listed under the 3Delight → AOV section. Finally, AOV Groups can be created in the Node Editor by pressing the tab key and typing dlAOVGroup.
Creating a new custom AOV
Click the + button to create a new AOV. A name field will appear so the new AOV can be named. Once the name is set, the new AOV will be added to the proper list and will be selected so that its value can be defined.
Assigning values to custom AOVs
Once an AOV is selected in the Color AOVs list or the Float AOVs list, a new element will be shown below the lists to allow defining a value for that AOV. It is possible to connect the output of a shading node to this element, as long as it is not the output of a surface shader.
The Node Editor can also be used to create that connection. The AOV Group node has array attributes for color AOVs and float AOVs; each array element consist of a AOV attribute, which defines the AOV name, and a Value attribute, which defines the color or float value produced in that AOV.
This element defines that "myColorAOV2" AOV will get the output of a checker shading node.
Primitive Attribute AOV