Creating an ambient-occlusion rendering pass with custom materials

…When we're rendering an ambient occlusion pass,…although it may look really neat in the…initial override, with the one material on everything,…we may want different results, and here's why.…I'll run a quick IPR, showing my ambient occlusion override on my scene,…and this override material is great for things like Mostly matte colored places.…For example, if we're dealing in warehouse or something…similar and we just need the occlusion to ground it.…However, I know I've got glass panels right…here at the top of the steps, and those…glass panels are uniformly white and heavy and…blocking actually the occlusion on the door frame beyond.…

I've also got ambient occlusion spilling on to my glossy floor and it's…going to deepen and darken the reflection that I worked very hard to get.…So, this calls for a custom occlusion.…Here's how I'm going to set this up.…I'll right-click on the Master layer, and…choose Overrides and Remove the Material Override.…Then, I'm going to select this layer, or…all the geometry and make a new render layer.…