compositing render layers - shadow pass problem

[israelyang]

here is the composited image.

[RiKToR]

Im not sure if your correct about what the shadow pass contains, I believe for most apps its projected shadows only. You then use an ambient pass to control the ambient light coloring and overlay the highight pass over the ambient to create the key light, or at least that is how I most commonly see it done.

[MinaRagaie]

noooop, shadow passes do not contain unlit areas...
instead u can try isolating your fill lights into seperate passes...
by coloring the fill light pass u can change both the color of the shadow and the color of the unlit areas :)

-Mina

[israelyang]

thanks for the reply

RiKToR
how exactly would you render out an ambient pass?

MinaRagaie
but what if there is only one light? then you wouldn't have a fill light pass.

[Wish]

Hi, guys!
1. Shadow pass is include self-shadowing if u use right shadow-pass shader.
2. Ambient have no effect onto the self-shadowing of your object. Self-shadowing is a diffuse component of a shader.

[jeremybirn]

thanks for the reply

RiKToR
how exactly would you render out an ambient pass?

MinaRagaie
but what if there is only one light? then you wouldn't have a fill light pass.

What you're looking for, the thing that would add color to both your shadows and to parts of your object that are unlit by the main light, is colored fill light. In real life, it's differently colored fill light that adds color to shadow areas. You can add a second light, dimmer and blue colored and coming from a different angle, as you fill light, and put it into a different render layer than the main light.

To render an ambient pass you could add your geometry to a new render layer, then create an ambient light in that layer. You can color the ambient light, or just tint the pass after it's rendered. By itself an ambient pass adds a flat, unappealing kind of fill light, but if you also render an occlusion pass to multiply the ambient with, then it can look more varied and interesting.

-jeremy

[Wish]

Occlusion will not give you self-shadowing! Occlusion is a part of global-illumination calculation. It's a fill light soft shadows!!! Only diffuse pass with shadow pass will give you shadows+self shadowing.

[jeremybirn]

Noooo!!

I hope that wasn't a reply to something I said?

-jeremy

[MinaRagaie]

MinaRagaie
but what if there is only one light? then you wouldn't have a fill light pass.

Sorry for the late reply... a Deadline was killing me for a while

Very few special cases where there's no Fill Light at all... (the only one I can think of right now is a Space scene... and it's even not perfectly without any fill)

most of the time you'll be using some technique as your fill light...
be it Dim lights positioned carefully in the scene... IBL.. FG... or GI.. or a simple ambient pass multiplied by an AO pass....
they all serve as a fill light... and that's what you can use to change the shadow color.

I did come across one shadow shader the do include unlit areas... (Puppet's shaders for MR) it worked great for avoiding AA errors I got on the shadow edges using maya's default "use Background" shader...
But still coloring shadows don't work as well as coloring fill... it kinda kills the directionality of the fill lights...

Cheers :)

-Mina

[israelyang]

Hi thank you all for your reply, much appreciated.

Mina
The ambient pass you mentioned here, is it the same method Jeremy talked about in his post?

[MinaRagaie]

Yup, Same thing.

[CGTalk Moderation]

This thread has been automatically closed as it remained inactive for 12 months. If you wish to continue the discussion, please create a new thread in the appropriate forum.