Shadow Pass Issue

[Diurno]

Hi all, i say immediatly that is a noob question, but i'm so new to the Fx Tree, then:

i've a scene, that takes long time to render, maybe 20 minuter per frame, and i've a good result but the shadows looks little grain; now i thought that i can split all in two passes: a diffuse one, and a shadows one; i've tried and i've this:



now my question is: it's normal this HUGE color difference between the two images? the one done in two passes it's very washed up, especially in the highlighted area?

[Letterbox]

Hi all, i say immediatly that is a noob question, but i'm so new to the Fx Tree, then:

i've a scene, that takes long time to render, maybe 20 minuter per frame, and i've a good result but the shadows looks little grain; now i thought that i can split all in two passes: a diffuse one, and a shadows one; i've tried and i've this:



now my question is: it's normal this HUGE color difference between the two images? the one done in two passes it's very washed up, especially in the highlighted area?

No that's not right, you shouldn't get that effect, what your probably doing is not using the right blending mode, over, etc.

There should be no difference, if done right, because the major benefit, is to rebuild the beauty pass, and perform "improvements" or "adjustments" with out having to rerender everything.

I'd take a look at some AE tut's (they are the most common out there) that explain how to rebuild from passes, then apply that reasoning to the fx tree.

Cheers
Terry

[Diurno]

i've tried that result after done a compositing Tutorial, that explain to use Sub blend mode with the Shadows pass; maybe i have that result cause i've some portal light and area light?

[Diurno]

Ok i've tried with this scene:

-i've created the scene with some simple geometry and 2 light: a portal light from outside and a soft light inside

and without separate passes i've this:



now for the separate pass i've done this:

-Pass - new pass- shadow

-render the shadow pass and i've this:



now for the DIFFUSE pass, i made an override with 2 parameters: the Soft Light Shadows and the Portal Light Shadows, i turned off them and i render:



-i go in the FX tree, take the 2 image imput, and composite with a Math Composite node in SUB (a-b) blend mode:



now lets' compare the results:



in the separate passe i've the same problem: where the light affect the object, it seems washed out.....

[julius]

In your single pass render, wa can see that the ball's shadow is different too than the separate passes rendering.

First of all, try to inverse your shadow pass in the render tree, and then, use the math composite node in multiply mode.

For the washed out part, your problem comes from your diffuse pass : try to render again without override, just disabling shadows in property editors of your lights.