OK let's introduce how to achieve specular reflection
in Arnold aiStandardSurface
and what attributes to control it
We've learned the meanings of these attributes
and what to adjust for different properties
In our scenes, we can more flexibly
adjust each object's reflection property
What we need to control is, we
simulate it through 2 attributes group
First, in aiStandardSurface, there's a specular group
This is very easy to understand
It's the second group in the attribute control
The second attribute group to know is called Coat
It's also to control this kind of specular reflection
Alright, let's figure out what
these two group of attributes mean
OK, for better showing change of its attribute
We opened another project file
Where is it
We click the open button
and find a folder called 33_jingmianfanshe
and open the file with mb extension
After opening, it's like a this small scene
Too show the effect and meanings of each attribute faster
we need to use it
OK let's see the Specular group
In Specular group, the attribute can split into 2 subgroups
one is commonly used, including the first 4 attributes
Let's see, these four attributes are commonly used
Them, the last two attributes here is seldom used
OK, after dividing them into groups
let's see firstly the meaning of common used four attributes
First, the Weight is very easy to understand
I turn on the real-time rendering here
As the bar goes left, the specular reflection disappears
As it goes right, the reflection gradually appears
It's very easy to understand
This attribute is to control the degree of specular reflection
OK let's see the next
There's an attribute called Color
By default we drag it to the left, gradually
its specular reflection disappears
Drag it to right, and the specular reflection appears
What's the difference between it and the Weight
Color attribute can control color to create more change
For instance,, when we simulate gold, its surface
will be attached a little layer of yellow
If we want to simulate green or blue gems
by adjusting the color and saturation we can
simulate such material
Color has one more control of color property than Weight
This is very easy to understand
Let's see the third attribute
It's an attribute called Roughness
If you've learned 3DMax or Vray Renderer
The Roughness and Glossiness have the same meaning
It means if the surface of model is smooth or rough
How much will it affect the surface
Let's see an image
OK let's three materials in image
The left object has 0.2 roughness
It clearly reflects the surrounding environment
As the Roughness gradually increases
the surface reflection becomes gradually becomes vague
It's very easy to understand here
The lower roughness is, the smoother its surface is
The more roughness is, the rougher its surface is
As the attribute increases, its bumps
becomes severer and severer
By decreasing the roughness
we can get an very smooth metal material with specular reflection
For instance, the faucet and sprinkler is closer to this feeling
If we gradually make it such rougher
it will look like a normal laptop
The base of screen generally is not very smooth
has a frosting feeling
It's achieved by increasing roughness
Let's see how much dragging the bar will affect
Currently the attribute is 0
So its surface reflection looks very clear
And we can see there's sun and sky
and there's mountain
As we drag this slider here
For instance, we adjust it to 0.22
Let's zoom in and see
We will find a lot of reflection here mix together
As we drag it to right
For instance, we set it to 0.4
gradually we can't see the sun and sky
They seemingly blend together
This affects the texture of surface a lot
If we drag it to an extreme value, 1
its texture looks very much like we only adjusting base
There's no specular reflection
We can contrast them to test out
The current roughness is 1
The Specular is 1 too
It means turning on the specular
reflection and set roughness biggest
Let's save current situation and click camera icon
And let's fully close specular
Wait for the rendering a while again
OK after rendering, let's observe it through contrast
The images with and without the Specular on are different
setting roughness to 1 and default
It's infinitely close to object with diffuse reflection
Let's introduce another attributes called IOR
I believe a lot of beginners won't know what it means
Let's see it
Set specular to 1 and set roughness to minimum
And then we will find
as the IOR attribute increases
our surface situation will look more and more obvious
It's like if the higher it is, the stronger reflection is
if the lower it is, the weaker reflection is
It's actually not completely correct
How do we understand it
Let's see a groupd of images
OK let's see the right area of image on the left
As we observe this area which is close to us
we will find reflection here is very weak
You can't basically see the reflection
More coloring of lake is like a kind of refraction
Through it we can see lotus leaves and grassland
As we gradually see far
to make it see this far place
we will find reflection info here is very strong
Through it we can see reflected sky
including trees and plants on the ground
How do we understand this kind of phenomenon
This phenomenon also calls Fresnel
Let me draw a sketch
For instance, this is a person
This is lake surface he's observing
He lowers his head to see area closer to lake surface
The angle forms here is this big
When we observe its angle
The bigger it is, the weaker reflection is
It's correspondingly this area in image
Reflection of area close to us is very weak
It's very hard to see
As he see far away
For instance, like this distance
Through seeing far away we will find
the angle becomes infinitely small
If further, it's out of the screen
then our eye is infinitely close
to parallel with lake surface
When its angle is smaller or closer to parallel
We will see its reflection is bigger
This is big and this is small
Its corresponding situation is like this area in image
The further we see, the stronger reflection is
OK let's observe another group of model
For instance, a bubble at here
we will find its edge is too white
It reflects sky severely
This is what we found
As our sight is falling on the center
the surface of the observed object and sight
gradually form a angle close to 90 degree
When reaching 90 degree
its reflection info will become more and more weaker
Let's draw a sketch again
For instance, this is our eye
OK
We see front
and then see a sphere like this
and then when we observe the edge of sphere
For instance, when we observe edge of sphere here
There's a tangent here
Our line of sight and tangent is almost parallel
so when we observe it,
reflection on surface will become stronger
Its corresponding situation is like bubble edge
As place we observe changes
when we see the angle close to 90 degree
Reflection of its surface will become very small
The phenomenon we get is close to this area
OK, after we realizing its surface has a physical property
It will generate influence for we explaining ior
IOR here is not to increase the overall reflection intensity
It actually increases range from center to outside
The higher this attribute is, the stronger
the reflection intensity in center is
The smaller this attribute is, the weaker reflection extent is
After we introducing principle
I believe you're clearer about the concept
For instance, currently we set it to 1
And wait for the rendering result
we will box select an area and only render its area
Let's save it
And we gradually increase it
increase it to 1.7
we will find center part gradually becomes stronger
Let's observe in edge area
Comparing to increasing reflection of center area
our edge reflection increasing is very weak
Let's save it again
We set this attribute bigger again
For instance, we set it to 3
Let's observe again
We will find change of its edge has no big difference basically
but the change of center when in 90 degree is very big
So far I believe you should understand
the real meaning of IOR control
What it controls is when the angle sight and object is 90
if we gradually increase it, the closer to center the place is
the stronger reflection will be
and the stronger increasing will be
and the lower edge part of increasing
OK, we can adjust IOR
There're a symbol with many lines
Click it
We will find there're many natural things
Different IOR refractive index
For instance, the refractive index of gem will be bigger
Refraction situation will be very obvious
Including the glass, it will be relatively smaller
and ice here will be smaller
OK after understanding core attributes
we will find there're two group of attributes below
It's to control others
Possibility of using it is very small
In this example we didn't use it
Let's talk about when we need to use it
Let's see these few reference image
In default situation let's simulate
The specular reflection of object's surface
We're very likely to get left status
but as we adjust attributes
Its highlight will change
It will not be a round shape
It will slowly become long strip shape
Its feeling is closer to the texture of
ring pull can from real natural world
After metal processing
the ring pull can will form a physical property
It's called anisotropy
If we go simulate some objects with anisotropy
Generally at this time we will change these two attributes
In most situations we won't change it
OK after learning specular attributes
We will find there's the Coat below
We just know it
Let's change a color
It's called coat
Let's carefully observe attributes here
It also has weight, color and roughness
It's completely same as above
Since they are exactly same
why do we divided them into two parts
Let me explain it
For instance, when we generally simulate a object
we're simulating the object itself
For instance, this is the object surface
and when we adjust it
we're simulating object's surface
but sometimes outside object surface
it will be attached by a layer of another object
For instance, we paint a layer of oil paint
poured some water on it
It formed a layer of membrane
How do we control this thin membrane
Through this coat
Let me change a color
For instance, its outer circle forms a thin membrane
Maybe it's oil paint or water
It wraps object itself
Just like this reference image
we use specular to simulate this layer of soil
simulate texture and coloring of its surface
but rainwater formed water accumulation
When we adjust water accumulation
We need to use Coat to control membrane of surface
For instance, there's a jar
Generally when we use highlight simulating
we're simulating the color of jar itself
A layer of sticker is attached on it
Its surface coloring info has many change
How do we control it
Generally we need to use coat to control it
OK after understanding the meaning of these two
I believe you're very clear
Only difference is this additional normal attribute
It's to control bumping info of its surface
Generally in what situations will we use it
Let's see an image again
OK For instance, this is our texture
We simulated it to certain degree
The Specular simulated its metal material
Use Coat to simulate its washed surface
After rainwater washing, some dewdrop and
trace of flowing will form a certain volume
We can't ignore simulating this kind of volume
Through normal we can simulate its bumping info of volume
Let's summarize this lesson
We mainly learned which attributes in aiStandardSurface
can simulate specular reflection
It's mainly divided into Specular and Coat
We've introduced in what situations we will adjust it
I believe after knowing the base control principles
The later adjustment will become more handy and confident
In next lesson we will come back to actual example
See if there is more advanced control for
some actual models, materials, properties
Let's see in next lesson