Checking 'consider for anti-aliasing' on multi matte pass changes beauty pass...?

[MartinB]

Our compers have been experiencing a few problems with fringing when using multi-matte ID passes and after abit of forum searching it seems it could be the 'consider for anti-aliasing' check box. I've not gone back over an older render/comp yet and checked, but one thing I have noticed on a test scene is that if I check that box, the main beauty render sampling seems to be affected.

Is this correct? and whats the proper workflow for making multi-matte passes

Below is two beauty render elements differenced, the only change between the two renders was checking 'consider for AA' on the multi-matte render element, I also upped the exposure to show the difference more clearly.



Cheers
Martin

[joconnell]

Yep, Using consider for anti aliasing will make vray use your pass to drive anti aliasing sampling. For example with the extra tex map, if you were to put some kind of checker map into it, vray would look at the edges where the squares of the checkers meet and then put in extra anti aliasing on yor main render along those pixels. With the multi matte element, it'll see areas of flat colour for the objects and do nothing, but where the red green and blue pixels meet along the edges, vray will put in extra sampling there. Be careful with extra tex when you start using things like vray dirt in there to give yourself a seperate AO pass, as if you've got consider for AA turned on it can give you a fair bit of a rendering hit.

[instinct]

Also holds true for high-value textures like the samplerinfotex in world coordinate mode. Causing REALLY high values and driving the sampler nuts hehe

[vlado]

Is this correct? and whats the proper workflow for making multi-matte passes

The correct workflow is to keep the "consider for antialiasing" option off for multimattes.

Best regards,
Vlado

[MartinB]

Cheers guys, that all make sense for when and when not to use consider for antialiasing and is good to know, but doesn't solve the initial problem of getting fringing when using multiMattes.

Below is the same test scene, with a colour correct node in nuke masked to the red channel of a multimatte, I've pushed the values to quite an extreme to show the problem, but this is a general issue our compers complain about.



EDIT:
I can understand why the fringing is occurring, the multiMatte mask is over black so its edge values fall off differently compared to the beauty render object which is over grey in this case, but I can't think of an elegant solution...

[vlado]

I can understand why the fringing is occurring, the multiMatte mask is over black so its edge values fall off differently compared to the beauty render object which is over grey in this case, but I can't think of an elegant solution...

Well, that's what the whole deep pixel data stuff is all about.

To do what you need conventionally though, you'll have to extract those objects into separate render elements; in 3ds Max this can be done with the VRayObjectSelect element, but I don't think we have it in Maya just yet - we can push it so that it gets in there sooner if you need it.

Best regards,
Vlado

[bigbossfr]

Well, that's what the whole deep pixel data stuff is all about.

To do what you need conventionally though, you'll have to extract those objects into separate render elements; in 3ds Max this can be done with the VRayObjectSelect element, but I don't think we have it in Maya just yet - we can push it so that it gets in there sooner if you need it.

Best regards,
Vlado

Do VRayObjectSelect can output specular/reflection/GI/Gi raw/etc etc....on a specific object ?
Or it is just a "beauty" renderElement ?

[vlado]

Do VRayObjectSelect can output specular/reflection/GI/Gi raw/etc etc....on a specific object ?
Or it is just a "beauty" renderElement ?

It's just the beauty. For the other stuff, look at deep pixel files...

Best regards,
Vlado

[manson]

hi,

we have also this fringe problem. would be cool to get this solved, if it is possible.
i was searching for this "consider for antialiasing" feature in the multi matte render element but i saw that it is only in the 2.20 release ;(

when i have to rerender mattes, i dont want to render the whole beauty. so i give the objects e.g a surface shader and the beauty renders black. this renders pretty fast and i have only my multi mattes render elements. but i have to turn the AA subdivs very high to get a good sampling.

we are using maya 2010 and vray 2.04. so is there anyway to get it for the older (2.04) version?

thx
cu manson

[bigbossfr]

hi,

we have also this fringe problem. would be cool to get this solved, if it is possible.
i was searching for this "consider for antialiasing" feature in the multi matte render element but i saw that it is only in the 2.20 release ;(

when i have to rerender mattes, i dont want to render the whole beauty. so i give the objects e.g a surface shader and the beauty renders black. this renders pretty fast and i have only my multi mattes render elements. but i have to turn the AA subdivs very high to get a good sampling.

we are using maya 2010 and vray 2.04. so is there anyway to get it for the older (2.04) version?

thx
cu manson

What is your settings ?
Set your DMC to 2-12, 0.005.

Ps : why do you not update your Vray ?

[manson]

My settings are dmc 2-40, 0.004, full adaptive(in dmc sampler: adap. amo.: 1, Ada. Thresh.: 0.005, adap. minS.: 8, Sdivs Mult: 0.01.
we started the project long ago with vray1.5 and and swith to 2.04 but it is not possible to change to 2012 now at the end of it ;(
but we have maya 2012 with vray 2.20 running but only for fx stuff.

i tested to render the multi mattes in 2012 and vray 2.20 and it worked.
it look like it is not implemented in vray2.04. ;(

cu manson

[bigbossfr]

My settings are dmc 2-40, 0.004, full adaptive(in dmc sampler: adap. amo.: 1, Ada. Thresh.: 0.005, adap. minS.: 8, Sdivs Mult: 0.01.
we started the project long ago with vray1.5 and and swith to 2.04 but it is not possible to change to 2012 now at the end of it ;(
but we have maya 2012 with vray 2.20 running but only for fx stuff.

i tested to render the multi mattes in 2012 and vray 2.20 and it worked.
it look like it is not implemented in vray2.04. ;(

cu manson

Like a say, try :
ADMC : 2-12, 0.005
DMC sampler : 0.8 - 0.005 - 32 - 1

[manson]

i tested it and it did not working. rendering looks the same ;(
i think when the beauty is black no AA sampling is done or only the minimum. so the MM render elements is also AA at the minimum.

[jasonhuang1115]

Hi Vlado, we are experiencing the same issue and wondering that beside implementing deep EXRs what would be a practical solution for Maya users assuming the VRayObjectSelect Render Element is yet available? (I checked the current 3.0 RC and didn't see this particular Render Element in the Render Global list)

Or any recommended 3D or comp workaround to cope with this edge fringing issue when heavy color correction is needed in Nuke on overlapping objects each with its own multimatte?

Thanks.

Well, that's what the whole deep pixel data stuff is all about.

To do what you need conventionally though, you'll have to extract those objects into separate render elements; in 3ds Max this can be done with the VRayObjectSelect element, but I don't think we have it in Maya just yet - we can push it so that it gets in there sooner if you need it.

Best regards,
Vlado

[vlado]

Actually the element is in the builds, but doesn't have a UI yet. Let me see if there's a way to create it with the Python callback...

Best regards,
Vlado