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Compositing 3D Passes
I’m having trouble figureing out how to properly composite my 3D rendered passes. I’ve read up on it, and watched tutorial videos, but I’m still having a hard time.
Here’s the rub. I can composite my passes just fine, they look great, but when I toggle on the Transparency Grid in my AFX monitor, all I get is black.
The current method I’m using is I’m putting the beauty pass on the bottom layer. It renders as a 32-bit image. All of my other passes render as 24-bit images. This is not something I have control over in my 3D app. So I work around this by rendering a separate alpha pass, and using my alpha pass ass an external alpha for all of my other passes that I’m compositing onto the beauty pass. Take the reflection pass for exampe. My comp would look something like this:
alpha (24bit)
reflecPass (24bit, mode is Add, TrkMat is Alpha Matte)
beauty pass on bottom (32bit)Then I try toggling on my transparency grid, but the reflection pass is blocking it. I’ve tried various combinations of modes and track matte options, but none seem to fit all the bills I’m looking for as far as providing a good look and also giving my the ability to have transparency behind my content.
Here’s a screen grab of what I’m doing:
https://www.dustinbrown.com/temp/transpGrid.jpg
And here is a link to my passes, just one frame of each, it’s less than 1MB.
https://www.dustinbrown.com/temp/bottle.zip
This is driving me bonkers, so if someone would be willing to either explain what I’m doing wrong, or set it up in AFX and take a screen grab of what they did, I would really appreciate it. I’m using AFX 7.0.
Thanks,
Dustin -
4 Replies
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You want to use a Luma Matte for the track matte, not an alpha matte as in your screenshot. The bottleAlpha.png file is itself fully opaque, so the alpha track matte won’t cut a hole in it anywhere.
You can dial down the impact of the bottleReflect layer by adjusting the layer’s opacity, or increase it by duplicating the layer over top of itself.
Walter Soyka
Keen Live, Inc.
Digital Media Design & Technology -
If I use Luma, no matter what blending mode I use, I loose the reflection in the glass:
https://www.dustinbrown.com/temp/luma.jpg
Inverse Luma gives me my reflection back, but I’m right back to square one and I can’t see my transparency grid with inverse luma:
https://www.dustinbrown.com/temp/invLuma.jpg
Any other suggestions are appreciated.
Thanks,
Dustin -
Sorry, I didn’t quite understand the problem at first. The luma matte for the glass is cutting out the reflections, because they are transparent in the layer without the reflections. The reflections pass requires a different alpha channel from your 3D app because different areas of the reflection layer need to be visible.
In other words, each rendered pass needs it’s own alpha channel to cut the proper areas.
Walter Soyka
Keen Live, Inc.
Digital Media Design & Technology -
Thanks, Walter. I ended up just using each pass as its own track matte. That seems to be going swimmingly.
-Dustin
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