Welcome to a physics based rendering or often shortened to just p.b. are.
So this is all about chasing realism getting those materials as close to reality as possible.
Now what we're talking about here is render time PBR rather than real time.
PBR in the viewport So we'll be talking about what is necessary for creating anything realistic.
When you go ahead and hit that F 12 key for a full time round or in fact if you've just got the viewport
on rendered mode as well.
We're going to get something looking like it does in the real world and that is critical for a lot of
work now.
When you focus on something that's physically based.
We're talking about how objects really are in the real world cycles itself is almost there but it does
miss a few points.
So you can't expect it to do perfect thing straight away.
You need to guide it along its way.
It doesn't calculate for now automatically of certain materials unless you tell it to and roughness
can be tweaked a little to make it a bit more usable.
And I have a look at those two things shortly correct but not always right.
Now this may sound a bit like an oxymoron but getting something physically accurate will mean it looks
correct.
It might mean however that it doesn't look right and that sounds like a very odd thing to say.
But if you've got something a vision that you want to create it might not be possible to create it in
the physical real world.
I mean that's the great thing about CGI.
And certainly if you or making a space ship they don't really exist at the moment or if you're making
an alien so making something look physically correct might not be the impact you want to create.
But it's a great starting point.
One sure at this stage whether it's modelling to get it looking physically accurate or materials it's
better to get to that stage first and then become more stylized rather than trying to jump to the stylized
whether it's over overexaggerated jawlines or an annamay style.
If you're talking about the modelling or whether you're talking about skin that glows or something along
those lines it's better to have a realistic first and then become more stylized because you're starting
from an accurate point.
So what is done and when it is very important when you render something it comes out perfect every time
the real world is not perfect.
Our eyes camera lenses etc are not perfect.
A small they have little imperfections in them which make well make life a little bit more interesting
and that's why sometimes when you're really stretching for that extra bit of photorealism having some
imperfections in the scene add a lot to it.
Things like depth and field focus glare lens flare are all added after the scene has been rendered and
this stage is called post production.
Or sometimes post processing.
Okay so what is wrong with roughness.
Well there is a massive drop off in sharpness between a value of zero and zero point one and then it's
much slower in terms of how it's changing after that so as not linear it drops off very quickly and
being non-linear it makes it very difficult to use because a small adjustment low down is going to make
a big difference.
We aren't going to use the maths node to try and correct this and will go home to learn a couple of
new node commands as well.
Now before we go in do that we just want to see here.
Default vs. adjusted so we have a ball a sphere that's in an environmental texture which is the photo
I have taken and we can see that with the roughness values the jump between 0 and 1 is quite extreme
but as we go along to just point five we can see that it changes very slowly.
Now using the maths node we can see a just how those values account collated with the slider and we
get a complete different effect.
And this is going to make it much easier to control and not.
You don't have to just apply this to roughness of course.
We're just using this as an example of how we can manipulate how something is working with something
like a maths node.
So let's go explore the maths node now and hop on over into a blender.
Okay so now we're over in blender.
I'm not gonna do this with a keyboard could do with a Q but I know I'm going to do a sphere.
Spheres look better in cubes.
Don't obsess Cubists a space.
So there we go.
Let's add a newbie sorry I'm going to make it smooth.
I'm also going to go to the subdivision's surface modifier and under the render settings just turn that
up to six.
Then it's going to be super smooth and want to look and have any horrible artefacts when it comes to
rendering.
I will add a material to its already and I'm going to set it to be a glossy shade up that's fine so
the only other thing were missing is if we hop over into rendered mode.
We don't really get much.
We get a grey ball because it's reflate in the grey environment.
So let's go ahead into the world tab.
Use nodes and of colour options.
I'm going to click the little dot to the right load in an environmental texture.
Now this isn't actually an environmental texture of I'm going to load in as such is just a picture of
I've taken.
If you've got other textures that you want to load em by all means do that.
Otherwise go to U.S. assets.
You should find two panoramas that you can pick from.
I'm going to pick this one here and I'm going to whiz over to the camera feed to see which view we've
got cayla.
So now they're really like that song going to go into first person moving mode.
Now you can see here this isn't a perfect wraparound text or anything like that is little she just panorama
taken.
So the world has ended there and started again.
So we want to be able to see some mountains and I quite like the look of that.
And then a heif 12 quickly just to see how that renders out.
Again this is important that you check your work often.
That looks absolutely fine to me now because it's lovely and smooth because of the six subdivisions.
We get a nice crisp border going round.
Okay so now we've got that.
Let's change this little box this outline up top.
Well I'm going to remove the lamp for a start.
I'm going to delete that from our scene completely and go change this to the 3D view and change it to
rended mode and view it from the camera.
So we get an idea of what's going on life now that we've done that there's an awful lot of black in
the scene so the know how that's going to pan out.
Hopefully not too bad but now we've got this.
In the scene we can switch this big area over to the node editor and trust me to get rid of the outliner
when I don't think we've actually got this sphere selected someone to go back to 3D view select the
sphere.
Now we've got it selected when we go to the node of to the node setup will be there.
Okay so there's a couple of things that we're going to have to add to our node setup.
One is a maths node and that can be found on the menu and go down to.
Converter maths and we'll plot that.
And that's the value output is going to go into the roughnecks.
That's what controlling.
Of course we lose the ability to control the roughness here because it's now being controlled by this
node we can change the type here so we can do loads of different options.
And the final thing that we need to do is have a way of controlling these values here.
So I'm going to add in another node a very useful node is in inputs because it's giving input I suppose
nice and straightforward and it's just value is a slider.
And from things like this we can join the.
It's to both of these for instance and then control them both at the same time now at the moment.
We can see if I said that point one.
It goes all fuzzy so that's not quite right.
I think we need to play around with this maths though and find the right selection of what's grouser
we're adding here so this is going to add point one to point five.
And what we want to do is I'm going to link these back up against us almost as if this is not here.
Incidentally you can also do that by hits selecting it and hit me M key for mute.
Ill undo that all together and then we're literally bypassing it.
And this value is now controlling the roughness directly.
So we want really the value here.
By the time you've gone up to point five it's pretty obscure We can see.
So to get an actual reflection we're doing things like oh point.
1 and No points nauts to an open or three etc..
Quite low value is where would be quite nice to be able to have them higher up.
So whatever we do with the maths node has got to lower this value.
And with that comes a challenge.
I would like you to go ahead and smooth the roughness.
Play with the maths node and its options.
Can you figure out a way of smoothing the sudden change where one moment the image is reflective and
then all of a sudden blurred out.
There is no right answer here because there are going to be a couple of solutions that work for what
we want to do play with it think carefully if you if you combine numbers how do you get a lower number.
Think about it.
And please do remember to save your results.
We aren't going to use it again shortly possibly an hour and give that a go.
Okay guys.
Welcome back.
Let's go smooth out the rough ness and play with that maths note.
Okay so back over him blend.
I'm going to unmuted the maths node.
Okay.
So if we how do we get lower values we can subtract.
McKay what happens if we do that so.
Is there a subtracts.
Yes there is a subtract and.
Subtract the value of that's going to clampett low so it's going to be zero essentially cause you can't
get less than zero with the roughness.
So it doesn't matter what this number is when it goes to point five.
It'll then be zero and then so that's just offsetting the problem that's not going to solve that's all
multiplying.
Mm okay.
So if we multiply it by itself.
So point 1 if you Times point by point 1 you get point nought one.
Now that's lower the value.
Okay let's see what happens then.
So we go to a point.
One are but looking a bit better.
I presume as we step up.
Yes that's looking much better.
So there we go.
There is one option.
We can multiply.
But that does give us not quite the flexibility I would like.
That does give us the a right answer in this case but there's something else we can do here as well.
So let's have a look at some other options.
Power.
So what we've done here by timing it by itself so point one times point 1 we've squared it so that's
the power of tippoo.
So if we go ahead and change this to power and we don't want it to the power of its self because it'll
get tiny butts.
If we set the value here to two we've got point one to the power of two and then it comes out here.
Oh case let's just test that again sir.
Point One Point Two.
Point Three.
Excellent.
That is working of course one.
So the power of two is still one.
In fact one to the power of anything is still one see you do get the hundred percent roughness as well.
If we go all the way up.
Of course one times one if you've got the power there.
So this gives us the other option of increasing this so we could do to the power of five.
Now I'm not quite sure what that's going to do.
Let's have a quick look at what a hold down Shift here so I can Mike remove this as we go across and
we can see that it really starts getting blurry much later on.
And this gives us much more fine control over those reflections or rather the roughness of that surface.
I think five is a little too high because that's going to start making it difficult the other way where
you can't really get it's where it's bunched up.
The other end if we do that.
So right after experimenting ifes I'm kind of settled if we go to point to here and we can compare it
bourges muting this.
No.
This power node here we can have a look in the top there.
And when we mutate we consumed it was like all it now is like.
So 2.5.
And we can go backwards and forwards.
I think a value somewhere between two and three works out really well.
Remember to show your work in the discussions.
Did you come up with a similar node setup to this.
If so brilliant if you came up with something different I'd love to hear your thinking how you worked
out how to teach maths know to use.
Did you approach it from a completely different way.
I've tried to talk through roughly my thinking there.
Obviously I've been playing with it for a while so I've got some preconceived ideas of what was going
on.
But if you're completely new to this.
I'd love to hear your thought process on how you came about completing this challenge.
And as always I will see you guys in the next lecture.