 | | | Paint F/X and objects with transparency....?? | Paint F/X and objects with transparency....?? 2003-12-01 - By zwp1@(protected)
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Quoting Duncan Brinsmead <dbrinsmead@(protected)>:
> When there is no or little alpha it is not necessarily incorrect. Some
> objects are fully transparent, and yet add color to the scene. In the
> case
> of rain the drops are clear.. it is the specular and reflected
> component
> that adds color to the image. ( if you make a sphere fully transparent
> then
> stick a reflection map on it it will not show up in the alpha channel
> ).In
> these cases you can render against black then composite with an
> additive
> composite.. no alpha and thus no need to block what is behind, we simply
> add
> in some more light. It gets trickier when you have a mixture of
> incandescent
> or glowing transparent objects and opaque objects with antialiased
> alpha
> mattes ... sometimes you may need multiple compositing layers.
>
I was thinking about rendering against black and getting just the specular
highlights...then using the exact same images as a track matte/alpha. This
provided less than desireable results however b/c:
a.) I'm ONLY getting the specular when I render against black. I don't get the
subtle curved in edges of the rain drop on the glass (the little bit of shadow).
So basically it just looks like a sliver of white running down the glass which
doesn't quite look right.
b.) I'm also not getting the curving/refracting of the image behind it.
So the effect doesn't quite add up...but I've come up with another slightly
more complex method to try out...I'll post it if it works (which would also
eliminate my paint f/x problem).
Thanks!
Z
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