Black Abosrbing Light

[jbdstudio]

Why won't black diffuse materials bounce light?

Here we have a srf with an emissive layer.
When the ground plane is black no light bounces.
If I make it gray light bounces.

Brian

[Travis Serio_cg]

Re: Black Abosrbing Light

ill dito that. I know the physics are correct, the whole black hole absence of light, but I too would like pretty black's in my scenes.

[garrett_jsaa]

Re: Black Abosrbing Light

A perfectly black material would reflect no light. These don't exist in the real world. Though I believe NASA is trying.

In V-Ray, make your surfaces "almost" black.

[Micha_cg]

Re: Black Abosrbing Light

I understand it so - color (0,0,0) means 0%,0%,0% reflection and color (255,255,255) means 100%,100%,100% reflection of R-G-B. So, if we try to be physical correct, than materials should get color values from approx. 5...220 .

[Travis Serio_cg]

Re: Black Abosrbing Light

i think the problem is that being physically correct isnt always attractive. So far vray is the only engine i've ever used where black doesnt play well with other colors.

[garrett_jsaa]

Re: Black Abosrbing Light

Going back to the original post, I am wondering if Brian wants the material to glow with a black background. In that case you could get that effect in Photoshop.

Or:

Model the air molecules.

Ha. I kid.

[Micha_cg]

Re: Black Abosrbing Light

I think, there are several ways to get effect - for example to set the black at value (1,1,1) and place a second light behind the first in direction to the black surface. So, this is extra light could be set at high values to get a lighting effect.

Why should a (0,0,0) reflect light? And how should I get a 0 reflection, if (0,0,0) would reflect light?

[jbdstudio]

Re: Black Abosrbing Light

I want to bounce light off of a black diffuse layer mat.
By the time it bouces nice i'm at gray.

Heres one at 10,10,10 I barely see my light bouncing.
So the next image I compensate by bumping the intensity
on the emissive layer but now I get blothcy bounces.

I know I can use photoshop but thats a workaround not a solution IMO.

Brian

[Micha_cg]

Re: Black Abosrbing Light

Looks like you use an emitter. Try a rectangular light (this produce "direct" light).

[Travis Serio_cg]

Re: Black Abosrbing Light

you're after this affect?

[garrett_jsaa]

Re: Black Abosrbing Light

I assure you a glowing object in front of dark surface does not rely on the black surface to bounce light. There is atmospheric light, which can not be rendered in V-Ray.

Photoshop is the solution (not a work around) for this type of glow, IMO.

[jbdstudio]

Re: Black Abosrbing Light

"I assure you a glowing object in front of dark surface does not rely on the black surface to bounce light. There is atmospheric light, which can not be rendered in V-Ray."

Okay so I guess these attached renders on the Chaos site weren't done in vray.
What am I missing?

I see black and glowing.

Micha,
The rectagular light didn't work. It was an idea.
Travis knows what I'm after.

Brian

[Travis Serio_cg]

Re: Black Abosrbing Light

I think it helps if there is a reflection layer added. Diffuse 0 RGB does seem to become a black hole. The math is correct, but it isnt always about the math =). I think it boils down to the shader itself. It appears that Black to Vray can only exist as an Ambient material and not truly a Diffuse material. I think what you want Brian is a Diffuse + Specular phong style material.

[garrett_jsaa]

Re: Black Abosrbing Light

I am not sure what's going on in the first rendering, but the second one does not have atmospheric glow.

[garrett_jsaa]

Re: Black Abosrbing Light

Take it into Photoshop and boost the contrast. You will see no halo of light.