White Border Issue

[Deracus]

Hi there

i got an anoying problem when compositing an image for a current project. Overlaying everything works like a charm, but when i tried to multiply my AO-Pass for a second time but with a mask to make the AO-Shadow on the ground more obvious, it gives me some neat white border around the masked area, which pretty much ruins everything...

I have tried quite some stuff to overcome this problem, but haven´t found a solution for it. What i have tried so far is:

- switching off premultiplied alpha in the rendersettings for all passes
- using a different format instead of half-float exr
- using higher AA-Settings
- switching on "post-multiply alpha" in the fusion-loader

And now i´m out of ideas...help me!

[origin]

show your passes please...

one thing to note, if youre using LWF workflow, do not apply gamma before you merge your passes. Use the gamut node after you merge all passes.
Otherwise white border will show up, especially if you have any invisible-to-camera objects.

I strongly recommend a gnomon video about compositing in fusion.Thats the best tutorial next to Thiago's Ice stuff Ive ever seen.

[Deracus]

Here are the passes and a Fusion-Comp

The Comp is different from the one on the image, as i tried to incorporate your LWF-Hint...but it doesn´t make any differnce...

http://rapidshare.com/files/282592316/Passes.rar

I hope RS isn´t a problem. I had to use it as the file was larger then the allowed attachement-size

[luceric]

I think you're supposed to multiply the AO pass on top and not used the Alpha of the AO pass at all. Have you tried this?

If I recall, the alpha in the AO pass is b.s. because it's just the same thing as the RGB information, plus the matte, and that makes it wrong because it should be fully opaque white where the objects are, and not shaded.

[Deracus]

Maybe i got you wrong on this one...but i am not using any alpha of the AO-Pass right now. The Mask-Info comes from a specific Mask-Pass (Black-White)

[origin]

hi, the problem comes from the fact that AA of your object after ao-multiply is diffrent than AA of object on white background. and maybe also because that mask was rendered with lwf

If you want to blur floor ao-pass it's better to render separate ao for floor.

[Deracus]

I tried to render a seperate AO for the floor but after i aplied it with the mask, it gave me the same error as before...so i thought it had to do with something else...

But i had a look into your comp now and maaaan...now i finally know, who i have to ask, if i have some weird Fusion-Problem again.

Thank you very much. Took me some time to understand everything as you use the channel bool node to invert instead of the color space node, which i use.
Also i have never ever used instances in Fusion before. I´m rather new to it, as i am using it for....2 or 3 weeks now...not very in-depth...

Learned quite a lot. Thank you for everything ;)


btw...mind explaining me whats the problem with the mask and the LWF?