Y buffer

A long time ago (maybe 7 years) i saw a Maya render with X Y and Z Buffers. That means that every channel has a dimension buffer.

Red ---->Z buffer

Green -->X buffer

Blue ---->Y buffer

for example.

So you see an image you cannot understund very well but has the information of the XYZ

It was used in the Lord Of the ring movie to make fog in the feet of the troll in the mines. I was wandering is there any Y buffer render in max? i would really appreciate that for a proyect i´m working on now...

Any help?

thanxxx