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View Full Version : Why are my shadows white?

jedimasta
04-02-2009, 09:49 PM
It's crunch time for us and as usual everything is going wrong. We're rendering out multiple layers from Maya, one of which being a ground shadow layer which looks like this:
http://www.media-geeks.com/images/articles/shadowlayer.jpg
The actual vehicle gets layered on top and looks fine. Final output requires that the tif has an alpha (that includes the shadow) so that the image can be placed relatively seamlessly on a dynamic background. The problem is, despite temp backgrounds looking good in AfterEffects, when the image gets dropped onto its intended background in photoshop or flash, the shadow looks like a white, glowing halo as opposed to darkening the area it is over:
http://www.media-geeks.com/images/articles/haloeffect.jpg
You can see the effects that have been applied here:
http://www.media-geeks.com/images/articles/effectcontrols.jpg
and the layer is placed in the comp with a normal mode. I've tried to premultiply the footage with white, black and straight-unmatted to no affect. I'm looking for any help I can get. It's supposed to look like this:
http://www.media-geeks.com/images/articles/intendedoutput.jpg

(this is the result of a screencap from AE, throwing a solid behind it. please remember, I NEED the transparency with shadow in the final output TIF. i.e. the blue MUST not remain)
jedimasta
04-02-2009, 10:22 PM
Oh, and just as an added monkey wrench, when I export as PNG.. things look perfect. Is there a bit depth difference between PNG alphas and TIF alphas?
scrimski
04-02-2009, 10:41 PM
Pngs have no particluar alpha channel, the transparency is stored in the RGB channels.
jedimasta
04-02-2009, 10:44 PM
would that make any difference in the outputs then?
scrimski
04-02-2009, 10:49 PM
Difference in what? Transparency?
As stated
Oh, and just as an added monkey wrench, when I export as PNG.. things look perfect. it obviously does.
It's not a matter of bit depth though.
jedimasta
04-02-2009, 10:53 PM
Why is there a difference in the transparency that comes built into to PNG and the Alpha that is embedded in the TIF?
Mylenium
04-03-2009, 04:52 AM
What's unclear about the matter? You are simply not interpreting the Alpha channel correctly.

Mylenium
jedimasta
04-03-2009, 04:59 AM
What's unclear to me is how I should be interpreting them. Is there an attribute in the output module for the TIF that I'm missing, or perhaps am I going about this all wrong and should the shadow layer be rendered differently in order to get the results I want?
Mylenium
04-03-2009, 10:50 AM
Alpha --> Premultiplied --> White as the background color?!

Mylenium
jedimasta
04-03-2009, 03:17 PM
Not to sound ungrateful for the help, but if you had read the original question thoroughly, you would have seen:

I've tried to premultiply the footage with white, black and straight-unmatted to no affect.

Unless you're meaning to premultiply the output TIFs with white, which I'm completely unfamiliar with. Can you provide a screenshot?
Sifer
04-19-2009, 06:58 PM
I would create a render layer override for the environment color of your camera to black for your shaddow pass, if you happen to be using render layers.
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04-19-2009, 06:58 PM
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