3d mutlipass compositing

[jetinanand]

Hi All,

1.I am looking for 3d multipass render footage including mattes for practise. I am learning multipass compositing. However i havent been able to come across

much footage for practise.

2. Also, I have queries about the ID mattes or the matte with RGB color. The queries are
a. why do we need them?
b. how do we use them while compositing?
c. how are they generated?

If you have any link to the footage or footage of your own kindly help me. It is purely for practise purpose.
Any link to tutorial or knowledge resource about ID mattes are also welcomed.

Thanks & Regards
Jetin Anand

[RoundPixel]

Don´t you have access to any 3d software, so you can produce your own 3d passes?

In case you don´t, or either you wouldn´t be asking, you can take a look at Darth Mojo blog, specifically this blog entry linked below might interest you:
http://darthmojo.wordpress.com/2009/...appy-new-year/

Anyway, i think you should try to become familiar with 3D to some extent, it would help you on the long run, even if you don´t plan to work as a 3d guy.

In this other link, you can find excelent plugins for dealing with openEXR in After Effects, .. and ... a gorgeous sample of a jet fighter by Rob Nederhorst, with 49 channels to play with (look at the bottom of the page)
http://www.fnordware.com/OpenEXR/

hope it helps

[token_kiwi]

in answer to question 1:

you can find some basic multipass renders here:
http://www.vfxtalk.com/tutorialfiles...lusionComp.zip

there is a tutorial to go along with it which i found helpful when i was first learning shake, i believe it is also available in after effects?
here:
http://www.highend3d.com/shake/tutor...ral/130-1.html

you can also try this:

http://www.3drender.com/light/compos...paceSample.psd

in regard to your second question about ID Passes-
a) why do we need them? so we can quickly isolate parts of the comp that we would otherwise have to rotoscope/key/some other form of extraction which would take much longer.
b)how do we use them while compositing? by reordering/shuffling the channels around. ie. if you are comping a beach ball sitting on a beach, you would render out an id pass that had the beach completely green, and the ball completely red, that way, if you looked in the green channel, you would see only the beach, and if you looked in the red channel, you would only see the ball. therefore, if you want to colour correct the ball only, you simply "re-order" (i'm using shake terminology here) the ID pass to show the red channel only, so you have a black and white mask which you can use to colour correct the ball without having to roto/key it or extract it some other way.
c) how they are generated? I'm going to use maya terminology here if that's ok- typically i would apply a surface shader to the objects and use pure red, green and blue, (so for example the red shader would have RGB values of 1,0,0.) alternatively you can crank up the ambient colour of the shader so it doesn't recieve any shading - you want the colours to be as pure as they can be.
you would then put this id pass on a seperate render layer and output it along with your beauty pass.

check this page out for an adobe- based explanation:

http://www.adobe.com/devnet/aftereff...pt2_print.html


hope that helps

[jetinanand]

thank you round pixel & token_wiki. you guys are great. i am learning a lot from these links. will post my doubts soon...

thanks guys

jetin

[elitevfx]

Just to letting it out there. Hugo Guerra and I have made tutorials for CmiVFX/FX Mogul, it's multipass comp tutorials. Find them here:

Part 1

part 2

Part 3

The 3D files, or atleast all the footage, will be available for download soon aswell. Keep an eye out.

[mboden]

Wow, elite thanks you and Hugo so much for putting that together.

[jetinanand]

thank you elite & hugo ... great resource !

[sgr]

I also typed up a walk through of how I used selection masks on textures for my final project at VFS - it's compiled as a PDF and would give you a general overview of the steps I did using Maya and Nuke but it can be used in any context and application environment.

Grab it here.

http://www.sgraae.net/dll/RGBSelectionMask.pdf

I am planing on striping the text and dumping it here in the site's tutorial section as well.

Hope it helps a tat as well.