Welcome to Diffuse and Specular Materials! So in
this video, well we need to understand these for getting
rendering just right. We'll be looking at the two in isolation and seeing what they
do and combining them to see the overall effect. And just
a reminder that we are still using Blender Render! so
Diffuse vs. Specular
reflections! Well both are types of reflection, and
Diffuse is essentially when light scatters, as it hits a surface,
and Specular is a direct reflection of the light
onto the viewer. Materials, in the real world, are often
a mix of the two. So a bit of physics for you all,
the Law of Reflection! So we've got the blue arrow on
the left, and that's the light coming in the angle of incidence of
of that light beam coming in. This is just a tiny photon hitting
this surface, equals the angle of reflection, that's the
light coming out of it. So that's the basic Law of
Reflection, and let's look at that in a bit more detail. So
Specular Reflection looks kind of like this! So a highly Specular
surface, almost 100% in this case, if I've got my angles and
everything right, the light beam comes in and comes out in exactly the same way
it came in, and that would produce what you would see
like on a mirror or on a lake, a still lake
reflecting mountains in the background. How picturesque! So that
would be almost 100% specular reflection, where you
get a direct reflection of whatever is coming in.
Diffuse Reflection, however, is slightly different, because
the real world is not all lovely, flat, and smooth,
we end up with a lot of Diffuse Reflection. As you can see here, the light's
coming in and going out is all over the place, so you
don't get
direct reflection. Just like when you look at your wall,
right now, it's probably painted in a matte or a satin
paint, rather than a highly glossy paint, which is more Specular,
and then, of course, you may have mirrored walls.
So let's hop over into
Blender and see how these act, when using Blender Render.
Alright, so I've opened up a new Blender file!
I suggest you save the work that you're working on. Now, the reason why I've opened up a new one is because
we're going to be playing about and experimenting, and we don't want to
do that in the chess scene that we're working with, at the moment. So the first
thing that I'm going to do is get rid of our cube that's here, because it's
not going to show off the Diffuse vs. Specular very
well, so I'm just going to Delete that from our scene.
I'm then going to Add, into our scene, the
Monkey, a bit more exciting a mesh! And
since the light is above the monkey, just behind it, as
we can see here, that little orange blob now, well
we will want to orientate our monkey so at least it's
facing that way. So I'm going to rotate it around the X axis.
Whoah, there we go! And that
will probably be enough, but I'm just going to rotate it around the Z, as
well, so the face is facing the light!
I'm going to quickly hop over into Rendered Mode, on the Viewport shading,
just to make sure that the face is getting the right amount of light,
and it seems it is! Now, a couple of things I want to do, that's a bit too
low poly for me; I do want to up it, so I can really show off
what the Specular and Diffuse shading can do. So I'm going to
turn on Smooth Shading, initially, and see what happens, and it's still a bit jagged around
the edge. So, as we've done in the past, I'm going to add a
Modifier, a Sub-Surface Division Modifier, just to smooth
this mesh out. So under the wrench, under Add Modifier.
So we're going to Add the Modifier here,
Subdivision Surface Modifier, under the Generate,
second column, third one up from the bottom.
And oops, that's done enough smoothing, I'm happy with that! I think if
it gets any smoother, we probably won't notice if we up it even one more.
Ah, there isn't a small difference there, but again, you get into
diminishing returns quite quickly, so I'll probably leave that at 2, for the
moment. So there we have our monkey! I think she's
called Suzanne? Yes she is! Excellent! So we need to
apply the material to that monkey there.
So now, create a new material and just call it Test.
So there we go! And this material, let's scroll down a little and
have a look at the options. So we have Diffuse and Specular. We're going to be
focusing on these two here, it's Shading, Transparency,
Mirror, Subsurface Scattering, Strand, Options, etc. etc.
We can go into those at a later time but not now, we really want to
focus on just these two here, because they're going to make up most of what you're going
to be doing, so I'm just going to hide all of that lot there. OK, so the
intensity on both of these simply turns up their values. So if
they're both down at 0, you probably guessed it that the
image is completely dark and
is not reflecting any light at all. In this case, it's absorbing
all the possible light. The Diffuse, when we turn that up, well
if it's all at 1 we end up with a very matte finish, so there's
lots of diffuse reflection coming from here. So
we have that scattering effect that we looked at earlier, so this would be
very similar to a terra cotta pot. So if we change this
to maybe that sort of color. There you go, ooh that's
a bit too pink now! Very close, I was the second click.
I'm not going to play about with this! So there we go, a sort of
terra cotta pot! But if you were to gloss that pot, you would
add some Specular to it, so that will give it some highlights. So we'll
bring the specular up and see how it looks. And in this case, this is looking rather plasticky
still, and we may need to actually change the hardness.
So if we lower that down, you'll find that the
highlights get more and more spread out, and if we make it really really really
hard, it goes up to 511, we end up with these
very fine wispy like highlights.
So that changes the apparent hardness or
sharpness of those reflections, and you can play about with those to your heart's content.
Ramp, well that changes the way that the color
is brought into the scene, and this, we can see here, enables a
lot more options. And we're not going to go into those, at the moment either, we just need to know
about these two items here. Now these two here, the
Lambert and CookTorr, they're the shader types.
So you've got five options of
Diffuse Shader and five options of
Specular Shader. Now, these change how the
Diffuse and Specular Shading is worked out, and
it does vary quite dramatically between all of these.
Fresnel, if I'm pronouncing that correctly, as you can see here has
changed it very very dramatically, and these are quite sensitive.
Let's turn it up, maybe, to 1.2 and maybe that down to 2.
So you get a very sort of chrome like effect going
on with the Fresnal shader, going on there. The CookTorr
on here, well if we change it we see we get much sharper.
I'm just going to change these, now you get a completely different feel and look
to your model, depending on which shader option you go for. Some of them will
be very very similar. I quite like this one, the
Warsido, or Wardiso.
I can't [Laughs]... Ah, here we go, it's "use a Ward
anisotropic shader". So there's lots of options
there, and you can change these about to your hearts' content and get the
actual end result that you want. That's gotten incredibly plastic
here, at this point, but there we go!
We can see that the Oren-Nayer
gives this new option down here, Roughness, so that
will increse I presume the aparrent roughness of a material,
making it slightly dark, by the looks of things. Now, this is quite a smooth
material, so I don't know whether we'd get a decent result,
playing about with it anymore.
Now, if we look behind the area
where we don't get any light, at the moment. Now, this is
again one of the things to remember with Blender Render,
you won't get any bounce off of other objects, but you can
fake some of that. I know we said we're not going to dip into
the Shading or anything lower, but one of the things you can do is
just make the material itself slightly emissive, as if it's giving off
light. And of course, it would give off light if there was something hitting the back.
So if you turn up the Emit value, ever so slightly, all of a
sudden, the back is not completely dark. One or two is absolutely
fine, and that just gives it a bit more detail in the background.
There are other options down here, feel free to play with them. One of my favorites
is Mirror and turning the reflectivity all the way up. Of course,
that's reflecting, what's it reflecting? Absolutely nothing! It's reflecting
the environment around it, but obviously, you can play with that to your hearts'
content, perhaps pop something in an environment and turn the reflectivity up.
OK, so to just finalize here, I've done the monkey
Suzanne, using all five different
Diffuse Shaders. So over here in the Outliner, I'm just going to turn them on
one at a time. So this is, as I've said before, it's Fresnel.
No it's not, the s is actually silent, so I presume it's frenel.
This is what it would
look like. If we turn Lambert on
we can see that that is ever so slightly different, as well.
The mini art is down here,
let's turn on the orin, and that's up
there, and then, finally the tune shader, and we'll just
let that render out. And you can see that each one is drastically
different from the last one there, completely different in their
appearance. So it's worthwhile
trying out the various ones to get the style that you
want.
Alright, a quick challenge for you guys now, a reflection challenge!
So assuming the same lighting conditions,
grab a pen and paper and name yourself a material that is almost 100%
specular. Then, think about
which materials you think have almost no specularity, that don't have
reflections on them.
Now, look at items around you and you will suddenly start
noticing this detail in objects themselves.
So pause the video now and give that a go!
OK guys, welcome back! Well looking around what
I had, I have my tea pot here, lovely
reflection in there and my little Bluetooth headset,
and they were very glossy and highly specular and
we can clearly see reflections of the windows, amongst other
things in those objects. So going on to a medium
specular, well my micphone stand is sort of a satin
finish to it and has quite clearly
defined specularity on it, but it's not
super reflective. The same with the toy train that I have on my
desk, for some bizarre reason, and I notice,
of course, there is a bit of high specularity in the wheel hubs and the
magnet there on the front but that's fine, the rest is sort of a medium.
Then finally, low specular, I've got an old Nexus phone, and the
back of it is very rubberized, so it doesn't really
reflect anything at all. In fact, in this case,
that leading edge there is really exaggerated, because it's a light quite
close to it. How did you guys get on?
I hope you now get
what Diffuse and Specular are, and I will see you
in the next lecture!