Why do we need photon map?

[mildse7en]

I found lots of tuts use irr map+ photon map GI methord. I think irr map for first bounce and direct for second bounce could produce good result, so I just wonder why use photon map as the second bounce, what is the benefit, faster or better quality?

Thanks!

[Da_elf]

when you get really good at it it gets to be really fast

[TRGraphics]

I agree, it is much faster than direct on secondary bounces. Especially on large renders.

Tony

[cpnichols]

Your biggest advantage for photon mapping is when you want to do a lot of bounces of light. On the order of 10 to 100 bounces. But with light mapping, this may all change.

[mildse7en]

Thanks for the all replies!