View Full Version : Shadow composite problem.

02 February 2003, 05:42 AM
I'm very sorry for even asking this, because I'm sure the answer has to be on the forums here somewhere, I just can't seem to find it, and I'm in somewhat of a time crunch, here.
Alright, I'm using buffer export to export my shadows to file. It's groovy. I got that. Problem is this: i have stand-in geometry that's recieving my shadows that I'm compositing into live-action film. My shadows are all fine, but my geometry is being anti-aliased against the stand-in geometry...which is very bad. In other words, when I bring in the moving geometry, I have really cool white halo's around it where it's been AA'd against the white geometry in the scene instead of nothing.

I hope that made sense. =)
Any ideas, d00ds?

I'd really hate to have to render this all twice. =)

Mike RB
02 February 2003, 06:26 AM
Make sure you set the surface properties of the stand-in object 's alpha value in the advanced tab to shadow.

02 February 2003, 06:31 AM
Yep, it's set to shadow density. But, for some reason, if you watch it render in the previewer as it goes through the frames, it renders WITH the stand-in geometry in there, even though it's only supposed to recieve shadows as alpha density. =P It doesn't show up in the final render, but you can tell it's been anti-aliased against it. It's weird as hell.

Mike RB
02 February 2003, 06:44 AM
use the matte color option in the object render properties and set it to the same as your background color.


02 February 2003, 06:49 AM
It's too bad I can't have a "matte image" instead of "matte color" =)

Mike RB
02 February 2003, 06:57 AM
dont render with your image in the bkg, render on black or whatever and them together in post.

02 February 2003, 07:00 AM
Yeah, i know this, but I dislike matting it against black. It makes it seem almost outlined if the composited object goes against something white, for instance. That's just me being anal, though. Black is 99.9% unnoticeable. I should just stick with that.

Thanks for your help, Mike.

Mike RB
02 February 2003, 07:06 AM
if you background is going to be green, use that, whatever will be the least noticable.


02 February 2003, 07:08 AM
The part that sucks is that it travels between several things in the background. Some light, some very dark. Yehaa for fun post. =)

02 February 2003, 10:27 AM
you could use a matte controll in composite afterwards. donīt know wich tool you use but I know that most apps like combustion or AE have a funktion where you can postprocess the matte with shrink, blurr to avoid the typical outline effect that happens when you have a cg element with alpha. as alphas are not antialiased they are not as acurate when you render with AA.

02 February 2003, 11:54 AM
Can't you map the background image onto the standin images as a front projection so they will completely blend in with the background?

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