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ambient occlusion

Posted: Wed Jul 28, 2010 8:50 pm
by deadalvs
i would pay 150 $ additional to my 2.1 license to get:

an ambient occlusion pass solution for maxwell with controlled radius/falloff (basic, as for example in mental ray) with an option to enable/disable on/behind different materials.
example: no AO on glass, but on interior wall corners "behind" it.

i'd accept even that preview "thingy" quality ! as long it's the same resolution as the main render.

* * *

there's just no other way to perfectly render the AO pass in an other renderer since there is no way to perfectly match the DOF.

since AO is just a geometric value i think it doesn't mess with maxwell's physical light simulation ideology.

* * *

who else is in ?

how much money can convince NL ?

Re: ambient occlusion

Posted: Wed Jul 28, 2010 9:12 pm
by zdeno
render ambient occlusion in other render engine.
use camera map UV to fit rendered picture as mapping channel

use this with Your materials - UVchannel 2 or 3

You will get great control with this. It sometimes fail with mirrors (camera mapping) .

I used this technic to achieve easy control of falloff fresnel. It is much more flexible than Nd roughness and 2 refl colors to GUESS what will you get after 24 h of render.

Re: ambient occlusion

Posted: Thu Jul 29, 2010 10:22 am
by deadalvs
this properly works with DOF ?

can you post an example with maxwell render, medium DOF and the AO pass ?

interesting .. but you'll have to convince me ... :)

Re: ambient occlusion

Posted: Thu Jul 29, 2010 12:10 pm
by dariolanza
Hello deadalvs,

Are you commented, Ambient Occlusion is just a geometric algorithm created to mimic real Global Illumination.

In the real world there is no such concept, and thus Maxwell doesn't use that sort of algorithm.

And using a different render engine will give you problems with DOF, or displacement, to say a few.

But anyway, if you want to create a pass of Ambient Occlusion with Maxwell (we know it can be useful sometimes for compositing purposes) we suggest you this workaround (on Maxwell 2.1):

- Enable in all materials in your scene the Shadow flag (to make them shadow receiver). Soon you will be made to do this in all the materials you create. (by the way, you may do not need to enable it on the emitters material themselves, as they may not receive shadows when on).

- On the Render Settings, enable the Shadow Channel exportation flag.

- Launch your render with MultiLight on (Intensity MultiLight, not Color ML which is incompatible with the Shadow channel exportation).

When your render is finished, and due the new Multishadow feature in Maxwell 2.1, you will get several shadow passes (one per each light source). The shadow pass corresponding to your Environment lighting is the ambient occlusion pass you are looking for.

Let me know if you find it useful.

Cheers

Dario Lanza

Re: ambient occlusion

Posted: Thu Jul 29, 2010 1:40 pm
by zdeno
dariolanza wrote:
In the real world there is no such concept, and thus Maxwell doesn't use that sort of algorithm.
Yes ;) as "hidden from camera" "hidden for GI" AGS materials and maybe a few more tricks.

It is very useful for NL to use "non physical correct or there is no such thing in real life"

Just stop it! have some pride to admit you don't want/know to do this.

Re: ambient occlusion

Posted: Thu Jul 29, 2010 2:24 pm
by tom
zdeno wrote:Just stop it! have some pride to admit you don't want/know to do this.
zdeno, the lack of respect in your words reaches to annoying levels. Your biggest mistake is constantly underestimating what others say and know. If I were you I'd try to be more polite and avoid making white noise. Don't forget, you pay for the license and it does not include randomly insulting people over and over.
zdeno wrote:Yes ;) as "hidden from camera" "hidden for GI" AGS materials and maybe a few more tricks.
The answer is "No". Not like "hidden from camera" or AGS etc and Maxwell does not have tricks at all. It's the illusion you created yourself. There are two things tend to confuse many of you very frequently. Being physically correct and being available in real world. In this concept, hiding things to camera is happening in a physically correct way no matter if it exists in real world or not. Same thing valid for AGS, too. On the other hand, Dario's explanation to Ambient Occlusion (using shadow pass) is the physically correct approach as it calculates the occluded GI in a physically correct form instead of several fake parameters other engines have. Trying to falsify him and/or Next Limit's philosophy is something, talking about "pride" is another. Now if you have one, tidy up yourself.

Re: ambient occlusion

Posted: Thu Jul 29, 2010 2:41 pm
by Maximus3D
Hm, reading what Dario wrote about no AO pass in Maxwell makes me worry that there will never be a AO based dirtmaterial. :(
I have to disagree with this because AO is a important part of 3D, it serves many purposes and even if a engine aims to be super-mega-realistic it should have the ability to generate a AO pass for artistic purposes for those users who wants to make use of it.

/ Max

Re: ambient occlusion

Posted: Thu Jul 29, 2010 2:59 pm
by tom
Maximus3D wrote:Hm, reading what Dario wrote about no AO pass in Maxwell makes me worry that there will never be a AO based dirtmaterial. :(
Max, you know; Dario's explanation is a workaround. Today, none of us can say X feature will not be covered by Maxwell in the future. It's just something certain we will not implement these things in the way others faked. We're also not neglecting the required tools for artists in any way. AO is one of the methods for creating topology based pass or textures but, it's not the best or most physically correct option. I mean, AO itself is a workaround to this problem. As you see, we're constantly improving the engine and adding more features. But, we're strictly trying NOT to make it a bloatware.

Re: ambient occlusion

Posted: Thu Jul 29, 2010 3:05 pm
by Half Life
This is why I requested a Zbrush Plugin for studio -- Zbrush makes dirt/cavity maps a breeze with no extra work on Maxwell's part necessary... AO need not apply.

Best,
Jason.

Re: ambient occlusion

Posted: Thu Jul 29, 2010 3:28 pm
by dariolanza
And what about enabling Shadows Channel, enabling MultiLight, and then getting the AO pass as the Environment shadow buffer?

Don't you think it is a nice workaround? quick, cheap and without the need to dirt the Maxwell's code.

This way you'll get a pretty ambient occlusion pass during the Maxwell render. Is the problem that we didn't named it as "Ambient Occlusion Pass"?
Do you really need that name on the image you are using?

Keep in mind that ambient occlusion is a "faking" algorithm (just like interpolated radiosity, and many more) much more easy to implement than the internal algorithms that are inside Maxwell, and that recreates the real behavior of light.

Cheers

Dario Lanza

Re: ambient occlusion

Posted: Thu Jul 29, 2010 5:55 pm
by zdeno
tom wrote:..... randomly insulting people over and over.
It is because of my poor english. I don't have too many words to be more subtle.

returnig to first post
There is example of using other engine generated map for achieving non-physical material in maxwell render.

ink&paint in 1.7.1

Image
Image

Re: ambient occlusion

Posted: Thu Jul 29, 2010 6:13 pm
by Bubbaloo
dariolanza wrote:And what about enabling Shadows Channel, enabling MultiLight, and then getting the AO pass as the Environment shadow buffer?

Don't you think it is a nice workaround? quick, cheap and without the need to dirt the Maxwell's code.

This way you'll get a pretty ambient occlusion pass during the Maxwell render. Is the problem that we didn't named it as "Ambient Occlusion Pass"?
Do you really need that name on the image you are using?

Keep in mind that ambient occlusion is a "faking" algorithm (just like interpolated radiosity, and many more) much more easy to implement than the internal algorithms that are inside Maxwell, and that recreates the real behavior of light.

Cheers

Dario Lanza
Hi Dario,

I think what is asked for is an ambient occlusion baking feature, so it can be used as a texture in a material. Doing it the way you suggested is limited by one view, while a texture based solution could be used in multiple views. I understand that with Maxwell's superb GI, ambient occlusion is not necessary, but a baked occlusion could be quite useful for material creation. As for terms, I like to call it a cavity map. :P

Re: ambient occlusion

Posted: Thu Jul 29, 2010 6:35 pm
by tom
render channel, shadow channel under skydome, composited result (using shadow channel in different blend modes + curves etc whatever you like)

Image

Image

Image

Brian, yes. But, texture baking is another aspect, you know... ;)

Re: ambient occlusion

Posted: Thu Jul 29, 2010 6:37 pm
by dariolanza
Nice example, Tom.

It is equal to the usual AO pass.

Dario Lanza

Re: ambient occlusion

Posted: Thu Jul 29, 2010 6:46 pm
by brodie_geers
Is there a way to create a render without shadows? To use this AO-type pass to it's fullest, it seems like you'd need a base without the effect. Otherwise, it's sort of like having a reflection pass and a regular pass (rather than a totally diffuse pass).

-Brodie