Seperating specular and reflection color tint

[Art48]

Is it easy to implement? I just had a case where I felt it will be useful for faking in certain situations.
Basically have one specular color and one reflection color, seperated.

[joconnell]

Here's a question for the chaos folks too.

A vray light with a simple colour will render faster than a light with a texture no doubt, since there's less sampling / changes to take into account. If you've got a texture in the light, the reflection portion of any material that sees the light will use reflection rays to accurately get the right colours and brightness. How does the spec portion of the render calculate this though? Is it taking an average of the texture pixel values on the surface of the light that it's specular rays "see" and boiling that down to a simple colour average? If so would it make sense for speed and cleanliness of the render to have a separate texture slot for diffuse light, reflection light and spec light? Or does the spec get derived from previously calculated reflection and diffuse values?

If there's a speed hit involved in calculating spec values from a textured light it'd almost be something like using simple rgb values for your diffuse and spec emission on the light, then a texture for the reflection emission which would be seen by your scene materials.

[svetlozar.draganov]

Is it easy to implement? I just had a case where I felt it will be useful for faking in certain situations.
Basically have one specular color and one reflection color, seperated.

Isn't it possible to do that via BlendMtl with two separate shaders for Specular and Reflection?

[vlado]

Is your question about the lights or materials? If it is materials, it should be possible to do it with a blend material, like Svetlozar suggested.

I just had a case where I felt it will be useful for faking in certain situations

What case was that? I'm curious since I'm trying to figure out how often such cases would come up.

Is it taking an average of the texture pixel values on the surface of the light that it's specular rays "see" and boiling that down to a simple colour average?

No. The specular is quite correct even for a textured light - which you can see if you turn off the MIS option for the light; in that case, the light will not affect reflections and its entire appearance will be calculated with direct rays. It will be noisier, of course, but will still converge to the correct result. If you are interested in the technical details, read the paper on multiple importance sampling.

Best regards,
Vlado

[joconnell]

Thanks for the explanation - just thinking on the control / speed optimization side!

[Art48]

Is your question about the lights or materials? If it is materials, it should be possible to do it with a blend material, like Svetlozar suggested.

What case was that? I'm curious since I'm trying to figure out how often such cases would come up.

Best regards,
Vlado

Hi,

My question is about materials.
How would I go about that with a blend material?

Our usecase:
An object (a cooking pot) has brushed steel material, the lid is like rotation brushed as in reality, the pot itself normal.
We have a warm scene, much wood, and kind of coldish/not so warm lights above the pot.
The sides of the pot look warm since the reflections of the wood tint the material. The lid is coldish because of the light the material gets from many directions above it (anisotropy).
I would tint the reflection yellowish/brown within the material but leave specular untinted so it gets the right light from the lamps but the reflections are tinted.

[svetlozar.draganov]

Here is how could be done:


1.Unlock HGlossiness parameter for the Reflection Shader and set its value to 1 - this tweak will remove the Specular from the shader.

2.Disable Trace Reflection option from the Specular Shader - this will remove the Reflection from the shader.


Scene: http://ftp.chaosgroup.com/support/sc...specular02.max