maxdepth setting

[MaTtY631990]

This question may have been answered before, but curious to know why the maxdepth value can go to a maximum depth of 2048, when a maxdepth of 16 is the fixed value that would be used for true unbiased quality.

thanks

[LudovicRouy]

I've use a value of 42 and 64 a little time ago when i make smoke or fire because there is a lot of "layers" of the same matérial so if i take 16 there was some dark area, these values are usefull for transparent material i think.

[radiance]

Hi,

Any unbiased engine uses russian roulette.
That means, at every bounce there is a probability the path will be ended.

If you set your maxdepth at 16, in reality most paths are only 4-7 bounces long or even less depending on scene.
If you have a 40% chance of killing a path at every bounce, and you set your maxdepth to 1000,
You will also get only a few bounces per path, and maybe, once every few million paths,
Due to the rigth random numbers, you may get a path that is say 100 vertices, and will give you a big bright firefly

Competitors that abuse the fact that we dont use maxdepth = 1000 by default are just tricking people into thinking octaneis not unbiased. In fact there is no discernable difference between anything higher than 16, you just improve the chance of a fireflies.

Leave the maxdepth at 16, or if you want less noise and less fireflies, use 8 or so, it will still look just as good.
Once you go lower than 8, you will start seeing the difference, a darker image and some light which has been reflected a lot of times will be missing or glass through glass may seem black.

Radiance

[MaTtY631990]

Thanks for the reply. I was unsure for quite a bit of time and actually made me wonder why the maxdepth limit could go to a high limit.

[gabrielefx]

Hi,

Any unbiased engine uses russian roulette.
That means, at every bounce there is a probability the path will be ended.

If you set your maxdepth at 16, in reality most paths are only 4-7 bounces long or even less depending on scene.
If you have a 40% chance of killing a path at every bounce, and you set your maxdepth to 1000,
You will also get only a few bounces per path, and maybe, once every few million paths,
Due to the rigth random numbers, you may get a path that is say 100 vertices, and will give you a big bright firefly

Competitors that abuse the fact that we dont use maxdepth = 1000 by default are just tricking people into thinking octaneis not unbiased. In fact there is no discernable difference between anything higher than 16, you just improve the chance of a fireflies.

Leave the maxdepth at 16, or if you want less noise and less fireflies, use 8 or so, it will still look just as good.
Once you go lower than 8, you will start seeing the difference, a darker image and some light which has been reflected a lot of times will be missing or glass through glass may seem black.

Radiance

I agree,
in fact a famous competitor uses the fake unlimited bounces option....useless...

[radiance]

Hi,

Any unbiased engine uses russian roulette.
That means, at every bounce there is a probability the path will be ended.

If you set your maxdepth at 16, in reality most paths are only 4-7 bounces long or even less depending on scene.
If you have a 40% chance of killing a path at every bounce, and you set your maxdepth to 1000,
You will also get only a few bounces per path, and maybe, once every few million paths,
Due to the rigth random numbers, you may get a path that is say 100 vertices, and will give you a big bright firefly

Competitors that abuse the fact that we dont use maxdepth = 1000 by default are just tricking people into thinking octaneis not unbiased. In fact there is no discernable difference between anything higher than 16, you just improve the chance of a fireflies.

Leave the maxdepth at 16, or if you want less noise and less fireflies, use 8 or so, it will still look just as good.
Once you go lower than 8, you will start seeing the difference, a darker image and some light which has been reflected a lot of times will be missing or glass through glass may seem black.

Radiance

I agree,
in fact a famous competitor uses the fake unlimited bounces option....useless...

Yup, Indigo renderer has pulled this schamble on its customers for a long time now...

Radiance