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Issue that research on many sites didn't resolve.

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Andrew Ronholm
Issue that research on many sites didn't resolve.
on Mar 12, 2011 at 6:44:41 pm

Hi there, I'm fairly new to After Effects, and I've been having a problem that I've done a lot of research on found many of the same answers, but still have found no answer to why this is happening. Or how to make it work.


I'm just trying to make a video or a image sequence with the background transparent[ie alpha or straight alpha channel]. Now I've done quite a bit of research and I keep getting the same answers. Check the box or boxes "Alpha Channel" and "Straight Alpha Channel". Render it in QT, Tiff, [I think TARGA aswell] or PNG. Now I tried both check boxes with all three formats, and imported them into after effects and photoshop. I still get that black background, and when I key it out-which is what I had to do in one of my videos with my own made green screen. Which you can see in my work at you can see a black halo around pieces in the video of the enterprise, and half transparent pieces in the planet shattering. I've checked the footage, it is millions of colours +, it does prompt me to choose in AE when I import it, and of course I choose premultiplied with colour black. But it still shows a black bg when I drag it on to my comp.

Now I think I've tried every type of format possible, and I'd like to think I've tried everything but if I really had, shouldn't it be working by now? I'm really not sure cause I'm still learning. I just want to be able to composite properly without having to make my own green or blue screen in C4D for the render.

Please I'm at my wits end. I feel I've tried everything, and this is seriously holding back my learning process. I mean I do enjoy a challenge, but life would be much easier without having to key it out. Also keying doesn't give me the perfect transparent bg that I need for compositing.

I hope I get a quick response, cause I'm dying to make my next comp!

Thanks Andrew.

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Tudor "Ted" Jelescu
Re: Issue that research on many sites didn't resolve.
on Mar 12, 2011 at 8:10:08 pm

Here's my answer from your other post in case you stopped checking that:

I do not use C4D, but rendering should be similar with other 3D apps. In the apps I use you need to select the object/objects you want to have an alpha channel and specify that you want that channel to be rendered for those objects. In some apps the alpha is rendered out as a separate sequence of black and white images that needs to be taken in AE and set as alpha for the RGB render.
I have worked before with RPF files that contain Zdepth data and with that you can composite in AE pretty complicated scenes. Here's a link that explains that much better than I could:
Hope this helps.

Tudor "Ted" Jelescu
Senior VFX Artist

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tim hetsch
Re: Issue that research on many sites didn't resolve.
on Mar 12, 2011 at 8:21:19 pm


there are many things that come to my mind, why the alpha isnt working properly in ur project... i recommend to post your project file or do a step by step tutorial.
You can try to get around the halo with effect -> simple choker.

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Andrew Ronholm
Re: Issue that research on many sites didn't resolve.
on Mar 12, 2011 at 9:46:24 pm

I'll post my project file. That honestly sounds like the easiest and fastest way to get the answer I'm looking for, then you can just open it and tell what it is that I did wrong.

One question though, where can I post my project file? Surely it can't be within this thread, can it? Either way I just put it up on my website, having one sure it great!

Here's the link Planet

I hope that HTML link shows lol.

if not here it is so you can copy and paste it....

Thanks for doing this to BTW, I really really appreciate your help. It's so frustrating when you try to do something the way every one says works and it doesn't. Thanks.

Andrew Ronholm: aka Extil3
Visual Effects, 3D Animator, Graphic & Web Design, and Writer

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tim hetsch
Re: Issue that research on many sites didn't resolve.
on Mar 12, 2011 at 11:44:02 pm

ok, the c4d render settings seems to be correct in terms of Alpha, you must be doing something wrong in AE :/ try right click on the footage in the project window -> interpret footage, there you can change the alpha settings.
2 tips for c4D, if you render a still,change Filter Value in Render Settings -> AntiAliasing Tab to Still Image. And if you upload a c4d scene: File -> Save Project and zip it - this way the extern images, ure using in the mats, are included.


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Jon Bagge
Re: Issue that research on many sites didn't resolve.
on Mar 13, 2011 at 2:47:03 pm

First of all, just to check all the bases, you have tried clicking on the 'toggle transparency grid' button at the bottom of the composition window? That should confirm whether AE can see your alpha channel or not.

AE has to put something behind your image since you can't see through your monitor... By default this is black (or you can change the colour in the composition settings), or it can be a grid like in photoshop.

If you can see the grid then you have transparency, and you can composite elements behind it. If you have a black border around the image then you've set it to interpret straight matte when in fact it's premultiplied. If you have unwanted transparency around the edge, then you've interpreted it premultiplied when in fact it's straight.

Jon Bagge - Editor - London, UK
Avid - FCP - After Effects

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Roland R. Kahlenberg
Re: Issue that research on many sites didn't resolve.
on Mar 13, 2011 at 3:49:13 pm

YUP!!! Sounds like a user error error. ;-)
DO the transparency thingy within the Cop Panel OR open up the footage in the footage panel and view the alpha channel by clicking on the alpha swatch (ALT+4).


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