Re: Binary Iris Alphas

["Robert Chapman" <tekano.bob(at)googlemail.com>]

yeah I get that a lot, in fact its happening in a scene im working on right now!  usually I would just sigh and use the rgb pass and color correct - but this time thought Id have a quick go to see if I could get to the bottom of this.  

My usual workflow is to crank the blend radius up to some ridiculously high number which gives the look I want in the RGB channel - but never in the alpha, just by lowering this value to just slightly more than you need rather than loads more helps (in my case) to massively reduce the amount of dodgy 'grey' in the alpha.  maybe tweaking the blend radius will work for you?

Rob C 

ps. im using blob particle ptype with static blur to get this particular look with genietail

2008/4/25 Eric Lampi <ericlampi(at)yahoo.com>:

That's exactly what I had planned to do if no other method was available.
Thanks,

E

 Freelance 3-D Animator, F/X Artist

----- Original Message ----
From: Morten Bartholdy <xsi(at)colorshopvfx.dk>
To: XSI(at)Softimage.COM

Sent: Friday, April 25, 2008 3:20:29 AM
Subject: Re: Binary Iris Alphas

A workaround could be to render twice and make the volume a nonshaded white
and use that for matte - should render fairly fast too.

Morten Bartholdy
3D & VFX Artist



----- Original Message -----
From: "Eric Lampi" <ericlampi(at)yahoo.com>
To: <XSI(at)Softimage.COM>
Sent: Thursday, April 24, 2008 5:12 PM
Subject: Binary Iris Alphas


> Anyone get odd Alpha's using Binary Iris?  I begand doing some tests, and
> came across this problem...
>
> Look at the attached image and you'll see what I mean.  The RGB looks
> fine, but the alpha is causing me to get these larger grey blobs in test
> comps...
>
> Any suggestions?  I know you're here Alan, but I figured someone on the
> list might have a solution too.  Maybe I am missing something in my setup?
>
> E
>
> Freelance 3-D Animator, F/X Artist

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