Hello
again and welcome to the second installment
of my procedural tutorials. In this
tutorial we'll be making a brushed
metal. It will focus both on the procedurals
used and on the Raytrace material
together with Shellac. Here's a preview
of the finished result:
If
you don't have a clue what I'm talking
about when I say procedural, I suggest
reading the help file that comes with
3dsmax. Or you can look through part
1 of this series, Procedural Wood.
Beware;
my style is not to write number specific
tutorials. Personally I hate that.
Which means this can get a little
lofty at times, but fear not, I'll
be using lots of pictures. Good luck.
Maps used
First
of all, lets review what we'll be
using for this shader.
•
Noise
map.
A very handy map that appears
in almost every single material
I make. Very useful little bugger.
•
Mix
map.
This map is impossible to do
without. The ability to mix
maps is essential to a good
material.
•
Falloff
map.
The falloff map is another map
that is incredibly useful. You
can use it to fade between two
colours or maps depending on
light/shadow, perpendicularity
to the camera etc etc. Read
all about it in the documentation.
•
Raytrace
material.
The raytrace material is the
basis for this shader. Read
more about it's features in
the documentation. I will only
touch a few of the features
in this tutorial.
•
Shellac
material.
I used this to get an anisotropic
highlight. The Raytrace material
doesn't support anisotropic
highlights, which means a workaround
is needed.
And
that's it. All you need to get a good
looking shader that is entirely procedural.
What do we want?
First
of all, lets stop and think about
how brushed metal look. In my head,
I had an image of almost parallel
grains, which creates anisotropic
highlights. After confering with a
few friends, I found out that I was
not quite right. It needed more randomness
and more of a crosshatch pattern.
The
easiest way to simulate this is by
using maps with parallel lines that
are layered, each layer having a slightly
different angle and size. I did this
by tweaking the tile and angle values
in the noise map. As you will see,
noise is a very versatile and useful
map. The mistake most people make
is to just slap it on and think it's
enough to change the noise type from
regular to fractal, maybe change the
phase and size. Usually you can tell
it's a noisemap a mile off if you
leave it at that. The noise map is
great, as long as you mix it with
other noise maps and other procedurals.
United we stand, divided we fall kind
of. Single noise map is (in my world)
a big no-no. Anyway, enough rambling
and onto material making.
Noise noise noise
First,
open the raytrace material and name
it Brushed. Click the bump slot
and pick the mix map. To make it
easier to navigate, name it "bigmix".
Click slot 1 and pick mix map again,
name this one "grain01".
I did this to get more control over
the grain. Now we can mix two different
grains with different angles and
get a richer, more random surface.
Click slot 1 again and this time
pick a noise map, name it "grain01_1"
(I know, the naming sucks, but it
matches the screenshots :).
Depending
on the angle you want the grains
to "travel", you'll have
to change the tile values. I wanted
horizontal grain and adjusted the
noise accordingly. Experiment with
different tile values to see how
it affects the grain. It's a good
idea to adjust the phase and offset
values to make sure the rest of
the noise maps doesn't look the
same.
Back
up one level and copy grain01_1
to slot 2. Name it "grain01_2".
Change the tiling values
again. I only changed the
z value to 50. Change phase
and offset to make it unique.
Back up again, copy a noise
map to the mix slot, name
it "grain01_mix".
Again change the tile values,
offset and phase to differentate
it from previous noise maps.
Now
we have a decent grain map.
In order to add more random
streaks, back up to bigmix
and copy grain01
to slot 2, rename it "grain02".
Now you just have to go
through the three noise
maps and change the values
and rename them from "grain01_1"
to "grain02_1",
"grain02_2"
and "grain02_mix".
I was a little lazy and
the only things I changed
were the Angle values. Look
at the images for specific
values.
Go
back to the bigmix level.
It's time to add the final
mix map. Copy grain01 to
the mix slot. Rename it
to "grain
mix". "Bigmix"
should look like this
now. Dive right in and change
the noise values once again.
To keep things orderly,
change the names of the
noise maps to "grain
mix_1", "grain
mix_2" and "grain
mix_mix".
And
the final bigmix map should
look like this:
Whew...
That's all the work we do
with the grain for now.
Go back to the root of the
mat.ed. and instance the
"bigmix" map to
the specular slot. Now for
diffuse.
Click
the diffuse slot, pick the
mix map, name it "diffuse
mix" and put an
instance of the "bigmix"
map in slot 1. Put a noise
material in slot 2, name
it "diffuse-color".
I used light blue/grey tones
in this map to give the
surface a slight variation.
It's more or less obscured
by the reflections though.
But you have the map there
for future use if needed.
As
you see, it's almost all about tweaking
the values until it looks good.
I spent a good part of two days
fiddling with noise values, specular
values, reflections etc. But it
pays off. What you must keep in
mind is that the material might
not fit all models straight away.
You will probably have to adapt
it to your specific scenes. But
once you've created a good looking
material, it's not that hard to
resize and refine it for other models
and/or scenes.
Next
up are the material settings, including
shellac, raytraced reflections and
more.
Highlights
Lets
start with the highlights. Brushed
metal has anisotropic highlights.
In short it means that the highlight
isn't a round white spot, but instead
lots of small parallel lines. I
won't go into detail on how it works,
Neil
Blevins has an excellent explanation
of that. Suffice to say that the
anisotropic highlight option is
the one we need for this job. Unfortunately,
the raytrace mat doesn't support
it which means we'll have to use
the Shellac material. Click the
Raytrace button and pick Shellac,
Keep old material as sub-material.
It should look like this.
Click
the Shellac material, name it "Anisotropic
Highlight". Change the
ambient and diffuse colours to black
and tweak the specular and glossiness
settings. You can use the image
as a guide. Place an instance of
the bigmix map in the bump slot
and the specular slot.
The
reason for this is to break up the
highlight and add to the realism.
It's important to remember that
the shellac material isn't affected
by the bump map in the underlying
material, which means you have to
instance the bump map if you want
the highlight to react according
to the underlying surface. In short,
without a bump map, the highlight
would just "glide" on
top of the bump map in the Brushed
material. Which would look bad.
Another good thing is by using instances,
you get fewer maps to edit which
speeds up any changes you make.
Lastly, turn on supersampling. Hammersley
is a good choice for bumps which
we have a lot of in this material.
Go
back to Raytrace material (Brushed)
and adjust the highlights. Since
the shellac material (Anisotropic
Highlights) creates the main highlight,
we don't need a strong specular
on the raytrace mat. I used very
low values overall.
The reflections
And
now for the render intensive part:
blurry reflections. The raytrace
material supports blurry reflections,
although they are evenly blurred
and not anisotropic blurry reflections.
But they are sufficient for this
material. Open the Raytrace
Controls rollout. Here you can
add a neat effect: reflection falloff.
It fades the reflection to a specified
colour or the background after a
set distance. This together with
blurry reflections adds a lot to
the scene. To get the blurry reflections,
turn on Global Antialiasing Settings.
Click the three dots to open the
Global Raytracer settings. Select
the Fast Adaptive Antialiaser, click
the three dots in to open the F.A.A.
settings dialog. Here you can specify
the defocusing and blurring of the
reflections. I really
recommend that you sit down and
render a few tests with it and read
the documentation about these settings.
You might need to adapt these settings
to your scene in the future.
To
give the reflections a final
touch, put a Falloff material
in the reflect slot, name
it fresnel. Change the falloff
type to fresnel and uncheck
"Override Material
IOR". Change the IOR
in the Basic Parameters
to something around 8,0.
This makes the object more
reflective on the sides
and less reflective head
on.
The
last map is another Falloff
map in the Ambient slot.
This uses the default values
and is just a nice touch
to fake bounced light from
the environemnt. You can
leave it out if you feel
like it or if you are using
a true GI solution.
That's
it. With some luck, your
material should look like
this when magnified in the
Mat.ed.
Here's
the mat.tree in all it's
glory. If you look at the
names, you'll see that it's
all instances... Full
mat tree.
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This
last paragraph is for professionals
only, USE AT YOUR OWN RISK!
The short short short version
You
can do it like this, or as a friend
of mine (named Iain)
put it:
1.
Create
sphere.
2.
Apply
grey material.
3.
Periodically
show it to people who are
never satisfied and tweak
it until it looks great.
I
hope this tut has helped you in
some way. If you have any questions,
comments, praise and/or job offers,
feel free to mail
me or drop by #maxforums @ EnterTheGame.com
or #CgTalk @ Freenode.netI usually
go by the nick Urgaffel or Urg|(something).
Big
thanks go to the Maxforums Posse,
the Brazil Posse and all the ladies
in da houze!
