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-   -   Paint Effects MATTE using Maya Software (https://simplymaya.com/forum/showthread.php?t=31283)

mariosaidvieira 02-11-2008 07:20 PM

Paint Effects MATTE using Maya Software
 
Here I am with another question about Paint Effects.

I read a lot about ZDepht issues and converting PFX strokes to polygons both on the docs and on the forums around.

But I didn't found nothing about creating a MATTE shader within this context: Paint Effects Objects and Maya Software.
I want to use Paint Effects Objects and render with maya software, but also I want to be able to create render layers for my elements: big tree, little tree, and grass. All with a trasparent background, as I am willing to add the background later within After Effects.
I suppose the typical solution when using mental Ray and/or PFX objects converted to Polys is to assign a [Surface Shader] and turn [Out Matte Opacity] to 100% black.

I tried assigning a Surface Shader to a Paint Effects Object, but it doesn't seem to work.
I also tried to set to 100% black all of the Paint Effects Object shading attributes (color1 and 2, incandescence1 and 2, tranparency and so on), but that really didn't work as a MATTE shader.

Sorry if it is a dumb question, but I wasn't able to understand it just by reading the docs or searching through the forums.

Thanks!

happymat27 02-11-2008 08:00 PM

Hi there,

if I understand you correctly you need to save your renders as a file type which includes an alpha channel (tiff, tga or png). When you import your images into After Effects or whatever compositing package you happen to be using it should detect the alpha channel and show the rendered geometry on a transparent background.

Hope this answers your question,

Mat.

mariosaidvieira 02-11-2008 08:15 PM

Hi happymat27!

Thank you for your reply!

Sorry, but I'm sure that's not the problem. I'm already using an image format that supports the alpha channel.
The Alpha channel actually is there, but it doesn't really act like a MATTE shader would do...

I'll try to explain better with a picture... I'll post it right away.

Thanks again!

Mario

mariosaidvieira 02-11-2008 09:14 PM

image
 
http://i38.photobucket.com/albums/e1...ALPHAMATTE.jpg

This is what I get when blacking down all the shading parameters for my PFX object, and using Maya Software.

It's a screen capture of Maya's render view first displaying RGB and second displaying Alpha.

Hope that helps to understand my doubt.

Thank you Mat!

Mario

happymat27 02-11-2008 11:38 PM

ok,

I'm nowhere near Maya at the moment so I can't try this out first but........

You could try setting the Matte Opacity of the grass shader and the ground shader to Black Hole.

Hope it works,

Mat.

mariosaidvieira 03-11-2008 06:00 PM

Hi Mat!

That's what I first thought about doing.
But since I'm using Paint Effects Objects (they're are not converted to polygons), as far as I know, I don't have that option.
That's what I was wondering: if there's no Matte Opacity control in Attribute Editor for Paint Effects nor a way to assing a normal Maya shader to a PFX object, how can I create a MATTE for it?

Of course I can convert the Paint Effects Object to Polygons and easily assign a surface shader (or any other Maya shader) so I can set MATTE opacity the way I want. The fact is that I don't want to convert them to polys.

I know that's a whole new issue: "to convert or not to convert" PFX to Polys, but the main reason I chose not to convert them to polys is that the conversion seems to completely change the way the objects are shaded. You can see what I mean with the picture attached below.
I just used a grass preset out of the box from the visor. As a PFX it renders quite nice. As soon as I convert it to polys, the shading turns out to be a lot less realistic and very flattened and washed out. I tried to tweak those polys shading a lot, but I really can't get even close to the result of the PFX object. I also tried tweaking lighting and shadows to no avail.

http://i38.photobucket.com/albums/e1...erttopolys.jpg

Thanks again for help! Hope we can figure out some solution for this.

Cheers!

Mario

ragecgi 03-11-2008 08:31 PM

Quote:

Originally posted by mariosaidvieira
As soon as I convert it to polys, the shading turns out to be a lot less realistic and very flattened and washed out.
Hi mario! Welcome to SM:)

What you are trying to acheive in Post-terms is called a "Holdout" matte or as Maya calls it, a black hole.

To answer your question, shading shouldn't be of any concern to you, as all you require is the alpha information to get what you want:)

So, I would suggest saving your scene as another separate Maya file, then convert your object(s) to polys.
Then apply a shader to the object, and apply the Black Hole setting to give you your "Holdout-pass", or black hole matte pass.

Then, simply render-out that pass giving you the matte you require for your normal scene to look correct in post:) (i.e. compositing)

Does this make sense?

If not, lemme know:)

mariosaidvieira 04-11-2008 10:17 PM

Hi Izzy!

Thank you for your kind welcome. :)
Nice and very useful to know the terms. I really didn't know it was called a Holdout Matte. Now I can google this up and study furthermore!

I don't know if I did quite get it, because I consider myself very noobie when dealing with compositing itself.
The way I understand, I should be creating this:
for example:
big tree pass - create another file in wich I convert grass and little tree to polys and apply Black Hole setting to them. My big tree will still remain as a PFX object, so it will preserve nice and correct shading.
Did I get it right?
Well... I think it really makes sense.

I'd better off testing it!

Thank you for your help Izzy!

Cheers

Mário


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