A Quantized-Diffusion Model for Rendering SKIN and Translucent Materials

[anchovy]

Perhaps, I gather the presets are done using fit data. It might be more intuitive to see what the curves are doing in several cases and work at matching the curves rather than as you say using a color swatch which can be visually misleading.

Also just so I understand can you or one of the gang there post a sample file where the green OJ isnt the case? I really do want to get my head wrapped around how to eliminate it within the existing model.

-Michael

[vlado]

How about this one? The settings are exactly the same as in your scene, and the material is still physically accurate.



Best regards,
Vlado

[joconnell]

That's the point - it's not really a color. If I knew better back then, I would have named it "scattering coefficient" or something. The scatter "color" represents the scattering coefficients in the volume for the red, green and blue wavelengths respectively. While it has three components and it's convenient to represent it as a color in the UI, it does not behave as other colors like diffuse, reflection and so on. If you put orange diffuse in a VRayMtl material, orange diffuse is what you get no matter how look at the material. However, since scattering happens in a volume, the light changes as it goes through the volume - what comes out orange at one end, may end up as green on the other (or blue, or red), depending on the material properties.

Are we kind of in a situation similar to what metals do with reflection? As in different wave lengths reflect differently in a metal and similarly different wavelengths scatter differently in different liquids / sss mediums?

Michael what is fit data? Is it similar to a brdf scan except for refraction / scattering?

[vlado]

So the pesky greenish tint bug is fixed now; one of the formulas for calculating the volume properties out of the sss color was wrong - it is also wrong in the original bssrdf paper that I followed

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

Wow congrats o.o

[vlado]

Hehe hopefully really fixed this time

Original code:


Fixed code:


Best regards,
Vlado

[bigbossfr]

it is also wrong in the original bssrdf paper that I followed

Best regards,
Vlado

Ahah, really ?

[vlado]

Ahah, really ?

Well, you know how most papers usually have one or two subtle mistakes - a plus turned into a minus, or a ' sign omitted somewhere, can make a bug difference

Best regards,
Vlado

[Morbid Angel]

So the pesky greenish tint bug is fixed now; one of the formulas for calculating the volume properties out of the sss color was wrong - it is also wrong in the original bssrdf paper that I followed

Best regards,
Vlado

I knew it!.. So will it be Skin material or Mtl 2 still?

[Morbid Angel]

Hehe hopefully really fixed this time

Original code:
[ATTACH=CONFIG]12588[/ATTACH]

Fixed code:
[ATTACH=CONFIG]12589[/ATTACH]

Best regards,
Vlado

This makes a huge difference vlado!

[Paul Oblomov]

Congrats

[Metzger]

WOW! That's awesome Vlado. Fixing everyone's code since 2001. Hehehehe

[vlado]

So in the latest nightly builds, there is an option in the sss material (in the Options rollout in 3ds Max, in the Extra Attributes rollout in Maya) called "legacy mode"; it is automatically enabled when loading old materials, to preserve compatibility, but is turned off for newly created sss2 materials. When this option is off, there should be no unwanted color shifts in the sss2 material. If you can test this and let me know if it works as expected, it will be very helpful.

Best regards,
Vlado

[Dariusz Makowski (Dadal)]

Maya 2013 nightly too?

Thanks, bye.

[vlado]

Maya 2013 nightly too?

Yes.

Best regards,
Vlado