a question for Christopher Nichols

[Mister3d]

Hello Christopher, this question arouse after reading this thread at cgtalk http://forums.cgsociety.org/showthread.php?f=21&t=271237&page=3&pp=15 , where you said that there are 4 ways to make an AO pass in vray:

Irradiance map with just 1 bounce

Skylight

Dome light

Dirt shader

 

But I thought that an ambient occlusion is based on normals calculation and doesn't bounce light at all, what dirt shader does. So why those methods, like an irradiance map solely for the 1-st bounce are called an AO? Or the point is that visually we get 1 direct bounce from a light source and visually it looks like an AO, so therefore we can use it as such?

Thank you.