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Best alpha option for Vegas users

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MistahTibbs
Best alpha option for Vegas users
on Jun 17, 2007 at 2:00:39 am

Hey all,

Vegas 6 user trying out the latest PI demo.

I've been playing with all sorts of combinations when rendering out a series of targa files so as to take advantage of the alpha channel.

I followed the tutorial that Elvis pointed to - http://www.wondertouch.com/tutorials/aharon/CNIA/cnia.html

Rendering out targa files with "Save Alpha" & "Create Non-Intense Alpha" checked.

I import the image sequence into Vegas 6 and set alpha option as directed - "straight - unmatted" and then....

I get nothing. If I change the alpha to undefined or nothing I get a black background and the sequence runs but not when I follow the directions of the tut. I realize it's for AE but the it should work with V6 or am I mistaken?

Any help is greatly appreciated as my purchase of PI is dependent on effective alpha channels.

sincerely,

MT



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Elvis Deane
Re: Best alpha option for Vegas users
on Jun 18, 2007 at 7:31:22 pm

You mean in a case where you are using both intense and non-intense particles, right? The problem is that Vegas doesn't have a transfer mode similar to Luminescent Premultiply.

But you get nothing as in the image disappears when you put it into unmatted? The alpha channel itself should show up in Vegas so long as you use TGA or PNG and check the Save Alpha box.



--
Elvis Deane!

The Apprentice Magician's Guide to particleIllusion

Wilbur of Wumbaberry


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Alan Lorence
Re: Best alpha option for Vegas users
on Jun 18, 2007 at 7:35:09 pm

Unless he checked "create non-intense alpha" and only had intense particles there -- they wouldn't be part of the alpha channel, and "nothing" would show. Maybe that explains it.





Alan.

http://www.wondertouch.com


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Tech Diver
Re: Best alpha option for Vegas users
on Jun 19, 2007 at 1:34:58 pm

Alan,

Could you or others please elaborate some more on this issue. Everytime I have used the "non-intense alpha" option in PI3, I see absolutely nothing in the PNG files that are generated. I don't recall at this moment whether the PNG files are completely black or transparent, but this option has never worked for me regardless of which effect I use (and I have tried this with dozens).

Thanks,
Peter


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Alan Lorence
Re: Best alpha option for Vegas users
on Jun 19, 2007 at 3:09:29 pm

The docs explain this in more detail, but basically when using "create non-intense alpha", intense particles do not contribute to the alpha channel.

For me, the only time to use "create non-intense alpha" (CNIA) is when you're doing smoke, or any other effect that has a "soft" edge. Otherwise, just use the "remove black bg..." option and make sure your compositing app interprets it as a straight alpha, not premultiplied.



Alan.

http://www.wondertouch.com


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Tech Diver
Re: Best alpha option for Vegas users
on Jun 19, 2007 at 3:59:43 pm

Thanks for the rapid reply. I understand now why I have been getting a blank alpha channel. I will continue to use the Remove Black BG option as you suggest.


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