*Most wanted tutorial topics*

[johnsmint]

i would like to see some blend, multilayer, complex metals :)

+1

[123joris456]

More indepth tutorial about SSS materials with examples like wax, milk, juice. I'd like to better understand when to use translucency, when refraction and when opacity.

This might help for now:

[maru]

I would say something like this:
Imagine that you have some object, and you cut it in half. Then observe what is going on at the surface and inside.

-translucency: when you cut it in half, you see a very thin "skin" or "layer" on top, a portion of light bouncess off the surface and hits camera, but also a portion of light passes through that layer, and then scatters in some media inside. Examples: grapes, skin, paper (thick)

-opacity: imagine that you form a ball out of smoke, and then cut it in half - this is uniform, and does not have any kind of surface, close to the edges opacity goes from X to 0 so it has soft borders. Examples: smoke, clouds, ghost (though I am not sure if ghosts don't refract light!).

-refraction: unlike smoke, this object refracts light, when you cut it, you see that object has no separate surface, it is solid and has the same characteristics at every point, on top and inside. Examples: murky water, wax, juice

At least this is how I see it.

[romullus]

Thanks maru, i will take that for now. Unfortunatelly i cannot cut in half every object i want, for some cuttings i would end up in prison for looong years ;]

[maru]

Yeah, that's why you so this in your imagination, full impunity! <3

[Ondra]

Opacity is used when the SSS medium has the same IOR as environment. So for example smoke - smoke is just air with some particles in it. Because of this smoke has no surface. You can simulate this with opacity. When used, there will be no boundary - all light will enter the medium undisturbed, and only in the medium it will be scattered.


Ideal Refraction is used when the medium has clearly defined, smooth surface, such as water, glass, or milk. Even though milk scatters light a LOT, its surface is still flat, as shown in clear, mirror-like reflections. The light partly reflects and partly enters the medium without scattering, and only inside the medium it is scattered.


Glossy refraction or Translucency is used when the medium still has clearly defined border, but it is very rough on microscopic level. This causes the light to scatter immediately upon entering the medium (and then possibly again inside the medium).



It is simple to choose from these 3 categories. Only tricky part is whether to use glossy refraction or translucency... you can say that translucency is an extreme case of glossy refraction, but this is more about trying what looks good instead of relying on physics/real world properties

[romullus]

Now that kind of info is what i always wanted to know. Thank you very much!

[Ludvik Koutny]

Yep, basically translucency is very, very close to refraction with IOR 1.0 and refraction glossiness set to 0.

Actually, if you ever need to control how much diffuse the scattering of translucency is, you can instead use refraction with IOR 1.0 and control refraction glossiness, if you then map refraction color instead of translucency color, and keep refraction glossiness at 0, you will see it looks almost same as translucency :)

[romullus]

A bit complicated for me to grasp that concept at the moment, but i bookmarked this topic, so i come back at it later for sure :]

BTW, in your strawberry tutorial you used IOR at value 1.0 or just slightly above. Wouldn't be more physically correct to use higher IOR, like close to fresnel IOR values? Did you do that for performance reasons or there's something else?

[Ludvik Koutny]

A bit complicated for me to grasp that concept at the moment, but i bookmarked this topic, so i come back at it later for sure :]

BTW, in your strawberry tutorial you used IOR at value 1.0 or just slightly above. Wouldn't be more physically correct to use higher IOR, like close to fresnel IOR values? Did you do that for performance reasons or there's something else?

Nope, i just did not find higher IOR values looking right. But i knew nothing has 1.0 IOR, so i tried to add at least some.

When i observed real strawberry, i found out that light doesn't bend and refracts inside that much, but at the same time, i did find that using translucency only made strawberries look too solid and not watery and juicy enough. So i added some refraction to the mix, yet i found out that when i increased refraction IOR, light bending was too significant and did not look like the real strawberry i was looking at :) So the only way to have still somewhat not completely solid, but also not oddly refractive strawberry was to use unrealistically low IOR :)

[GestaltDesign]

Would like to see in depth render elements workflow as well in particular with Fusion and Nuke!!
Strawberry SSS tutorial is superb by the way, the right level with a real world case, user workflow and scene download. Top job guys!!

[steyin]

Thought of another one:


Displacement maps. I know how to make them and use displacement for the most part, but any more knowledge would be beneficial, especially for making some nice brick materials.

[Christa Noel]

very very good explanation from maru and ondra, I really appreciate those kind of science :)
btw, I never study light physic or any science about it. so what is "medium" in ondra's theory above??

[Eder_Xavier]

ABOUT CLEAN NOISE FASTER ON INTERIOR SCENES..... I´M SURE THAT COULD BE A GREAT HELPFULL TUTORIAL.....

[Christa Noel]

ABOUT CLEAN NOISE FASTER ON INTERIOR SCENES..... I´M SURE THAT COULD BE A GREAT HELPFULL TUTORIAL.....

hi, I think corona helpdesk has your need. check this, https://coronarenderer.freshdesk.com/support/solutions/articles/5000501983