Original subtitles

And now it's time for a quick digression.

from my experience and the way I work, in every lighting project there comes a point when the

basic light scheme is pretty much nailed for the most part and you know it's good and you

are satisfied with it, everything works together just fine, from there it makes sense to change the

perspective and give some love to materials before getting down to the lighting details.

materials in computer graphics dictates the way the light rays bounce off or travel through

surfaces and the influence of shaders on the overall look cannot be overestimated,

so in these of topics subplot I guess we can try enhancing our materials with the subsurface-like

transport effect and spend a few minutes casually talking about material properties in general.

so we have strategically placed our key light behind the subject, now what if we allowed some

part of this light to actually penetrate the translucent surface of this object and

exit at some different point? I'm talking about the subsurface scattering effect or

subsurface slide transport as it's called sometimes. as we have mentioned already, by

default this effect was disabled in our demo scene, what we can do now is strike it back on

by reconnecting the loose dot that you can find in the shader editor back into the subsurface

scattering slot. doing that will open the way for some really intriguing lighting calculations.

what we need to do is select our main mineral

open the shader editor in the top window, you can press Shift F3 if you want to

do it via shortcut, there you will find our principal bsdf shader with a subsurface socket

and the loose dot that needs to be dragged onto this socket. subsurface scattering simulates

semi-translucent objects in which light rays enter, bounce around then exit in a different place. aside

from the sub surface slider that controls the amount of the effect, there is the subsurface

radius drop down menu where you can control the coloring or the tint of the effect. there

are three channels there, red, green and blue and you can tweak each one separately. for example you

can tweak the red one to increase or decrease the amount of red light scattered around. so

yeah basically that's how you give this mineral a sapphire, ruby or whatever else tint. aside from the

subsurface radius there is one more parameter that allows us to tint the the subsurface scattering

effect which is subsurface color, but I find it slightly hard to achieve really saturated colors,

it's a little bit unpredictable, so that's why I resorted to use the subsurface radius instead.

now let's quickly explore the nodes that would go into the subsurface slot.

I'm going to Ctrl Shift Click to preview this node alone

and basically there is the color ramp that receives the original diffuse texture then

makes it black and white and adjusts the contrast of it, the brighter the color the

more scattering and vice versa. now Ctrl Shift back onto the principled bsdf... okay... so it's a

mechanism of tweaking the variable surface scattering, then we should just grab the loose

dot and hook it up into the subsurface input and we should be good to go! the contrast can

be tweaked by moving the flags closer to each other within the color ramp node and the power

of the effect can be tweaked by adjusting the... the tone or the value of these flags, for example

by making it darker you will reduce the amount of scattering. so one mineral done, a few more to go.

I will go through every object one by one really quickly except the table, so let's select this

stone in the background, click on the dot and connect it to the subsurface input. now do the

same with this one and the one in the foreground has no subsurface scattering so no need to touch it.

here's how it looked before and after subsurface scattering applied. once again the position of our

main light complements the subsurface scattering effect *so much* because not only the shadows fall

in the direction of the camera and the reflections go in that direction as well but... the light... uh

scattered through this stone also exits in the direction of the camera if that makes sense and

it all clicks because of the position of the key light in the reverse key manner. cool, right? :)

now while we are reviewing our materials, let's go through other properties of our principle bsdf

shader just in case. what else do we have here that can be controlled? we have this specular

slider that controls the amount of reflections. that can play a major role in how the object

would look under certain lighting conditions. how many glossy rays in Cycles does it reflect,

that could be important. and the other really crucial thing is how glossy is it or how diffuse

is it on the other end of the spectrum. we have yet another color ramp here for controlling the

glossiness or roughness, which is the same thing but inverted. you can play with the

position of the flags to make the certain portions of the object look wet for example,

let's disconnect this texture from the roughness input for for a second... so basically the low

roughness means that the object is super glossy, surprise (!) and the higher roughness brings it

closer to the perfect diffused look. with the color ramp implemented we achieve a so-called

variable roughness, meaning that these certain portions of the object reflect the light in a

more glossy manner while the other are way more dull. the details like that may not seem like a

big deal, but what is lighting in 3D if it's not interactions between the emissive surfaces and the

materials basically. so here comes the variable roughness color ramp, Ctrl Shift to preview,

dark means glossy or even mirror-like if it's black bright means rough and diffuse and then

control the contrast via the flags within the color ramp. okay, Shift click on the main

material... what else do we have here? the object can be metallic if the metallic slider is pushed

all the way to the right, or it can be a perfect dielectric material if the slider is set to 0.

lastly if you feel like turning this object into a diamond, feel free to experiment with

the transmission slider that controls the object translucency, how much light passes

through the object, it works similar to subsurface scattering but in a slightly

different manner, it doesn't necessarily scatters the light around, it lets the light pass through

just like glass. as they say, not everything is made of clay and transmission shows just that.

the transmission roughness controls how clear is the object transparency, at the

higher values it can make the interior or volume portion of the mesh seem murky,

that's what it does. aside from that there is a good old Albedo texture or a diffuse texture

at play that adds the base color to the object. Ctrl Shift click to preview it really quickly...

that is the base color of the object that affects among the other things how much light bounces off

that object. so there was a quick rundown of the properties of the mineral shader, principled bsdf

that can be tweaked alongside the subsurface scattering, I tried to keep the material fairly

generic and fairly well balanced for the tutorial though, it has a little bit of everything, it's not

a super super glossy nor super rough, it has some subsurface scattering, it has some color but not

overwhelming amount of saturation in it. so that was a quick digression to bring the material and

lighting interaction to the foreground for a second. that is important for 3D lighting. now

with that in mind and with the added beauty of subsurface scattering letting sunlight

bounce around the object, let us return to our cinematic lighting setup and keep upgrading it.