https://i.ytimg.com/vi/0Gt6hotxOD4/hqdefault.jpg

A set in Maya is a collection of objects or components (for example, geometry objects or lights). Grouping objects into sets allows you to make certain changes to multiple objects at once.
MtoA can use Maya sets to apply Arnold rendering overrides to the objects inside. This allows you to override any attributes of the objects that are members of the set, which means you can affect a large amount of objects without changing the properties individually.

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