Optimizing renders for non photo real look

[redlad]

Hi guys,

I am testing Corona now for possible use in a children's TV series. I'm getting a pretty good result looks wise, pretty close to what I was getting with Mental Ray. I was wondering are many of you using Corona for non photo real types of work? Some questions I have:

Is it possible to put a limit on the reflectivity of a given shader, so that it only reflects thing in a 2 meter radius around it for example?
If you are getting really heavy noise in the shadows and just noise in general, what is your general 'fix' for this? Is it a case of just letting it render for longer? Do you have any tricks for adressing this?
What is the best combo of primary & secondary bounce for GI?

I'm not aiming for photo real - things can be cheated. if Corona allows it of course ;)

Hope you can help,

Cheers

[maru]

Generally Corona is a physically-based renderer so this might be pretty tricky.

Is it possible to put a limit on the reflectivity of a given shader, so that it only reflects thing in a 2 meter radius around it for example?

I don't think so. I don't know of such thing.

If you are getting really heavy noise in the shadows and just noise in general, what is your general 'fix' for this? Is it a case of just letting it render for longer? Do you have any tricks for adressing this?

Letting it render longer will always improve quality. But you probably can't wait infinitely so the other option is to change render settings. See these guides:
Noise in GI or direct light? https://coronarenderer.freshdesk.com/support/solutions/articles/5000516731
Noise troubleshooting https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983
"Best" render settings https://coronarenderer.freshdesk.com/support/solutions/articles/5000516729

What is the best combo of primary & secondary bounce for GI?

For interiors - usually PT+UHD.
For exteriors and scenes where GI is not dominant - usually PT+PT

[Ludvik Koutny]

Faking it in Corona usually does not lead to any performance or visual benefits...  often quite contrary.

Best would be to post some example of what you are trying to achieve. People often wrongly assume that stylized looks has to necessarily be NPR rendering, while even Pixar uses physically based path tracer for their new movies.

And it's very easily possible to construct for example toon shader network in Corona.

[Juraj]

while even Pixar uses physically based path tracer for their new movies.

I was going to write the same :- ).

What you request, is not stylized rendering, which today is used as artistic choice on top of physically based behaviour (which doesn't equal photorealism ! just that lights, and reflection naturally happen in places where they should, and you don't need to fake them).
Rather, heavily tweakable renderer where you choose to which extent you want certain features to interact and mostly tweak bias to get speed (or perhaps sometimes even art direction).

With that in mind, that's not what Corona might excel as it's based on out-of-box realism and easy/simple approach rather then flexibility robustness, but I would say the same, simply try it.

Unless you tried it, and you're battling noise&render time. Which again, is different issue altogether, to which the answer is mostly to accept it.
Corona doesn't really accomodate the type of workflow in lie of "ambient light instead of GI + AO" for example. It works best when you align your workflow to how it works.

[redlad]

Generally Corona is a physically-based renderer so this might be pretty tricky.

Is it possible to put a limit on the reflectivity of a given shader, so that it only reflects thing in a 2 meter radius around it for example?

I don't think so. I don't know of such thing.

If you are getting really heavy noise in the shadows and just noise in general, what is your general 'fix' for this? Is it a case of just letting it render for longer? Do you have any tricks for adressing this?

Letting it render longer will always improve quality. But you probably can't wait infinitely so the other option is to change render settings. See these guides:
Noise in GI or direct light? https://coronarenderer.freshdesk.com/support/solutions/articles/5000516731
Noise troubleshooting https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983
"Best" render settings https://coronarenderer.freshdesk.com/support/solutions/articles/5000516729

What is the best combo of primary & secondary bounce for GI?

For interiors - usually PT+UHD.
For exteriors and scenes where GI is not dominant - usually PT+PT

Thanks for the reply, I just wanted to test Corona out. I have used Mental Ray for years on really successful TV shows, it worked very well for what we wanted. Obviously it has it's issues, but we just worked around them. I think Corona could work for us, but it's just render time I'd be worried about. I doubt I could get a noiseless render in 10 minutes a frame. But I will continue testing.

[redlad]

Faking it in Corona usually does not lead to any performance or visual benefits...  often quite contrary.

Best would be to post some example of what you are trying to achieve. People often wrongly assume that stylized looks has to necessarily be NPR rendering, while even Pixar uses physically based path tracer for their new movies.

And it's very easily possible to construct for example toon shader network in Corona.

Thanks, I will see if I can post some examples if I have more questions. I'm aware Pixar are using physically accurate rendering for their films now, yes ;) It's an awesome renderer, I have tried it a few months back.

[redlad]

while even Pixar uses physically based path tracer for their new movies.

I was going to write the same :- ).

What you request, is not stylized rendering, which today is used as artistic choice on top of physically based behaviour (which doesn't equal photorealism ! just that lights, and reflection naturally happen in places where they should, and you don't need to fake them).
Rather, heavily tweakable renderer where you choose to which extent you want certain features to interact and mostly tweak bias to get speed (or perhaps sometimes even art direction).

With that in mind, that's not what Corona might excel as it's based on out-of-box realism and easy/simple approach rather then flexibility robustness, but I would say the same, simply try it.

Unless you tried it, and you're battling noise&render time. Which again, is different issue altogether, to which the answer is mostly to accept it.
Corona doesn't really accomodate the type of workflow in lie of "ambient light instead of GI + AO" for example. It works best when you align your workflow to how it works.

Cheers for the reply Juraj, I will continue to experiment with it. It's just another way of thinking while using Corona, another way of working.

To be honest, as I said to one of the guys above, render time on TV shows has to be quick, so that's my main fight right now - getting clean results in a short amount of render time. We could even try running a denoise pass on top of our renders. I know some big studios do this in their workflow so it's nothing strange.

In terms of look though - I was getting some great results in a short amount of set-up time with Corona, using the conversion script. The results looked very similar to what I was getting with Mental Ray. I had a noiseless render in Mental ray in 10 mins, but with Corona I reckon I would have to let it run for about 40 mins to be clean noise wise. I'll continue to test.

Thanks

[redlad]

Just a question about GI lads. If I wanted to reduce the bounce intensity from a certain object, have any of you done anything like that before with Corona? For example if the ground is giving far too much bounce (even if physically accurate) and the director says he/she wants far less influence of ground colour affecting other objects in the set. Or does the nature of Corona simply not allow this?

[maru]

Just a question about GI lads. If I wanted to reduce the bounce intensity from a certain object, have any of you done anything like that before with Corona? For example if the ground is giving far too much bounce (even if physically accurate) and the director says he/she wants far less influence of ground colour affecting other objects in the set. Or does the nature of Corona simply not allow this?

See "2. Practical usage" here:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000529341
Hope it helps!

[redlad]

Just a question about GI lads. If I wanted to reduce the bounce intensity from a certain object, have any of you done anything like that before with Corona? For example if the ground is giving far too much bounce (even if physically accurate) and the director says he/she wants far less influence of ground colour affecting other objects in the set. Or does the nature of Corona simply not allow this?

See "2. Practical usage" here:
https://coronarenderer.freshdesk.com/support/solutions/articles/5000529341
Hope it helps!

Thanks a mill Maru, that's what I was looking for