Author Topic: Ambient Occlusion (AO Pass)  (Read 35355 times)

2013-06-30, 09:58:30

Nupsi

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Hi,

I don´t get how to use AO with corona. I did found the AO-material, but I´ve no clue how to use it, because it´s always just black. My first idea was to put it into the self illu-slot, but in another thread someone said that this would be the worst thing one could do. So how do I enable AO in general (or is it already enabled?) and how do I get a AO-pass from corona?

And I know this is kinda OT, but which render setting do I need to change to get a better and more uniform illumination for interiors? Using the standard settings (PT+HD/PT+PT) produces noticeable shadow-blotches in darker areas.

Thanks in advance :-)
Nupsi

2013-06-30, 12:07:01
Reply #1

maru

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If you want to render an AO pass you have two options:
-in render elements add a Corona_BRDF_AO pass
or
-in render elements ad a Corona_Texmap pass and set a AO-enabled material in its "texmap" slot

If you don't want it on a separate pass create a material with CoronaAO map inserted in desired slot (for example diffuse colour).


About splotches in shadow areas: depending on your scene you can try increasing PT samples in HD Cache settings to about 1024 or 2048 or in "lights" section increasing Lights samples multiplier to 4-8.
Marcin Miodek | chaos-corona.com
3D Support Team Lead - Corona | contact us

2013-06-30, 18:41:31
Reply #2

Ludvik Koutny

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Any kind of artifacts on still images when using HDcache are extremely rarely caused by the insufficient HDcache accuracy. They're a lot more often caused somewhere in the scene, mostly by poor modeling or some crazy materials.

About AO pass...  BRDF AO seems pointless and will be soon removed. Official way to create AO pass is to use Corona Texmap element and plug Corona AO map into it... as Maru already pointed out ;)

Rendering AO pass to cover blotches in corners is a ridiculous way to solve that kind of problem. It is as if you had your shoe untied, and you would solve the problem by removing the lace from your shoe, killing a random person, then dissecting their body, tearing arteries out of it, then putting them on your shoes to replace laces and tying them up, instead of simply tying the untied lace ;)
« Last Edit: 2013-06-30, 18:45:29 by Rawalanche »

2013-06-30, 19:57:14
Reply #3

Nupsi

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Thanks for your replys. AO works fine as you described, maru. But I think I´ll stick to Mental Rays AO-pass for now, because it´s just so much faster.
And I´ll check my scene for any mesh- and/or material-erros, Rawalanche. But both, scene and mats, are really simple and straight forward. Increasing the light samples did helped though :-)

Thx and best regards
Nupsi

2013-08-10, 08:16:00
Reply #4

amol91939

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When I Add the Element Its Showing Can't Create Output File Error Can Anyone Help Me On This Topic   

2013-08-10, 09:13:30
Reply #5

Ludvik Koutny

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Thanks for your replys. AO works fine as you described, maru. But I think I´ll stick to Mental Rays AO-pass for now, because it´s just so much faster.
And I´ll check my scene for any mesh- and/or material-erros, Rawalanche. But both, scene and mats, are really simple and straight forward. Increasing the light samples did helped though :-)

Thx and best regards
Nupsi

AO pass should be nearly instant, definitely faster than Mental Ray's :)

2013-08-10, 09:21:09
Reply #6

Ludvik Koutny

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I just made a quick test to verify, and i get my AO pass nearly clean in the first minute of rendering. And it gets rendered with the main image.

I am also very curious why do you people need an AO pass with brute force renderer. This is not mental ray, you do not have any missing contact shadows to fix there. Only thing that will applying an AO pass gives you is a lower photorealism and more CG looking output. I can imagine using AO map for any kind of procedural effects, but for Corona, you should not really be adding contact shadows that are there already.

2014-01-14, 17:54:01
Reply #7

steyin

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I just made a quick test to verify, and i get my AO pass nearly clean in the first minute of rendering. And it gets rendered with the main image.

I am also very curious why do you people need an AO pass with brute force renderer. This is not mental ray, you do not have any missing contact shadows to fix there. Only thing that will applying an AO pass gives you is a lower photorealism and more CG looking output. I can imagine using AO map for any kind of procedural effects, but for Corona, you should not really be adding contact shadows that are there already.

If AO were desired (sometimes my office prefers a more CG/stylistic look) would you recommend using AO in material setups instead? Also, if doing an AO pass with the texmap, do lights need to be disabled/deleted like in mr?

2014-02-04, 11:57:23
Reply #8

chilombiano

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Ravalanche. I found and find BRDF AO very useful in the type of work i'm doing. And existing as where it is right now doesn't bother too much in my opinion. There is a lot more to cg outside the scope of arquitectural rendering where a BRDF AO pass can be used. I find most concerning and surprising that you guys are taking it out based on just the way you use it ( or not ) .

My two cents

Cheers

2015-07-17, 15:29:44
Reply #9

Luke_Wilkins_3d

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Why the hell is Corona AO pass so ridiculously complicated? I can't even see any options for it in the render elements? Where is the shadow matte? shadow catcher is a pile of arse, and difficult to set up? Paying for this engine.

2015-07-17, 16:10:43
Reply #10

Ludvik Koutny

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Why the hell is Corona AO pass so ridiculously complicated? I can't even see any options for it in the render elements? Where is the shadow matte? shadow catcher is a pile of arse, and difficult to set up? Paying for this engine.

20 seconds to set up... doesn't seem very complicated to me


Obviously, usage of every 3ds Max renderer will require at least some degree of technical skillset and learning abilities. If someone lacks these properties, there's not much we can do about that from our side...

2015-07-20, 07:58:08
Reply #11

vkiuru

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I am also very curious why do you people need an AO pass with brute force renderer. This is not mental ray, you do not have any missing contact shadows to fix there. Only thing that will applying an AO pass gives you is a lower photorealism and more CG looking output. I can imagine using AO map for any kind of procedural effects, but for Corona, you should not really be adding contact shadows that are there already.

It has its uses. The AO debate gets covered every time a new render engine emerges and is easily one of the most pointless ones to go through. We are not all going for realism all the time (mind you, with commercial work this is not always by choice), and our way of using post processing should not dictate which render engine we use.

2015-08-07, 15:51:33
Reply #12

mike_kennedy

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AO is a stylistic thing and tightens up contrast in your compositing later on. It's a fake for sure, but it can add a bit of pop and contrast.

2015-08-17, 20:56:02
Reply #13

rfletchr

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About AO pass...  BRDF AO seems pointless and will be soon removed. Official way to create AO pass is to use Corona Texmap element and plug Corona AO map into it... as Maru already pointed out ;)


Aside from some lofty self righteous sense of whats "correct" why would Corona want to remove a functional useful tool? We use AO in about 60% of our shots, we'd be boned without it.

2015-08-17, 23:04:44
Reply #14

Ludvik Koutny

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About AO pass...  BRDF AO seems pointless and will be soon removed. Official way to create AO pass is to use Corona Texmap element and plug Corona AO map into it... as Maru already pointed out ;)


Aside from some lofty self righteous sense of whats "correct" why would Corona want to remove a functional useful tool? We use AO in about 60% of our shots, we'd be boned without it.

That was very, very old post. Over two years now. Initially, there was no Ctexmap render element, and there was render element that was named CoronaAO. It computed ambient occlusion but also with reflections, and you could not disable those reflections what so ever. You could also not control any AO parameters except radius. No fallof, no spread, no include/exclude, nothing. It produced by default undesired results, and you had no control over it. So it was removed and replaced by Ctexmap workflow that allows you to do Regular AO pass but also with more flexibility, such as include/exclude, background color override, spread control, and also being able to put maps into AO color slots.

Here's a quick tutorial on doing AO pass with Ctexmap: