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This isn't
really a tutorial just a study of one channel,
diffuse. Which is the absorption of light.
This tutorial is intended to be general in
nature and is supposed to apply to almost
every 3d package out there. Max users will
have a problem understanding this because
diffuse in 3dsmax is color. I don't know what
they use for the channel that simulates the
absorption of light. Every thing in this world
has sort of a diffuse channel. Diffuse is
responsible for the display color. Although
in the computer generated world, you can go
ahead and add a bump map, (which simulates
depth on a pixel level which can be procedural)
or even add a color map to give it some values
of hue. But one of the most overlooked and
most powerful channel in my opinion is the
great diffuse. Using diffuse you and simulate
shadows and any area you'd like. If any of
you are keen of Radiosity also known as Global
illumination, knows that this lighting technique
adds the element of diffuse by bouncing light
at all angles to give you the "best lighting
situation". So certain areas that would
naturally be hidden by an overlapping object
gets shadow. Which is a great way of making
something computer generated look real, or
believable. One of the earliest cg shows that
I know of was Beast Warz. For computer animators
the show was a fun thing to watch and was
evidence that cg is getting more popular in
the film and television industry. I didn't
really see too many episodes, but from what
I saw it looked to fake. Which was probably
due to bad lighting situations but I believe
that alittle bit of diffuse would have help
it a lot. Another newer cg show is Action
Man, Starship Troopers, and Max Steel. Just
by looking at these shows you will see a huge
difference in quality. Its more tasteful and
is full of light and shadow, unlike Beast
Warz. So our universal goal in this world
is to refrain from the Beast Warz "Look"
and never look back.
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So when
you create a diffuse map keep in mind the
areas that receive shadow. Good way to understand
that is through example. A army of samurai
is standing up over looking the horizon wile
the sun sets. Just by reading that one sentence
you get this picture in your head of all these
soldiers. The most experienced 3d artist/Animators
see more then just that. They see. The army
for one, some un they're trousers, some wearing
silk garments. Then the majority of them are
wearing Heavy plated armor. Each piece of
armor overlaps each other as the lay. Then
if you dig deeper into the armor, you'll see
that each plate has their own carvings and
etchings. If you were to texture map the armor
you would first thing you would think about
is the relief it has. Parts are sunken in
and other parts protrude outward. So below
each piece that protrudes outward, assuming
the light source is the sun, you would then
paint about of dark gray under it. Then are
render time it will appear darker then the
rest of the armor.
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Diffuse
is also a great way of applying dirt to an
object. by scattering black you can create
variations in the map that would make it appear
dirty. You can even use it to wear down certain
areas. Like a mech for example. Around the
areas where there are joints; you might want
to add some dark shades to the diffuse channel
on those areas. Or around the edges were friction
occurs would be a area of wear. Thousands
of ideas come to mind if you just think about
the light source and predict possible shadows.
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This
first render is just of the color there are
no bump or diffuse maps applied.
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This
next render below shows alittle bit of bump
and the beginning of a diffuse map.
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This
render below shows the final Color, Bump,
and Diffuse map that I used to create this
image.
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Here
is the Texture I used to create the crate.
Which can be taken be any digital camera or
scanned in.
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Now I'd
like to talk alittle abit about how the crate
was created. By the look of the final render
it would seam like each board was modeled.
Which is in fact false, all it really is,
is a box. I'd show you the wire frame but
you would be surprised to see a box. After
I got the photo which could be of a bench
out in the park a boardwalk near the beach
or even a wooden fence. Either way this similar
image is very easy to find. Next in photoshop
I selected each piece of wood and put them
in their own layer. rotated them duplicating
them and flipping them over again. I even
selected and copied some nail heads and placed
them around to add more variation. It also
a good idea to dodge and burn parts of it
to add even more variation.
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the file for ya if you'd like to see:
cratemap.psd. |
| Flip through layers
to see how they're assembled. to get a decent
diffuse map flatten the image and goto mode
then gray scale, then back to RGB. Next goto
image adjust levels and move the arrow in the
center to the left for make it lighter. You
might want to experiment with it till you get
what you want. It also to a good idea to add
contrast to the image. Then save a copy as bump
map. Take the images that doesn't have the contrast
applied and mabey add a blur to it if its too
sharp. Now this is where you have to think of
where the shadowed areas are. Since the center
of the crate. Where all the boards are horizontal
would recede and the boards surrounding it on
the edges are infront of it. So now with a soft
bright and low pressure, paint in around the
inside abit. Save and render. If you aren't
happy with the simulated shadows go back and
either lighten and darken areas till you get
the proper effect. |
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Below
I have a sample diffuse map.
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| That's all. I hope
you realize the power of diffuse, good luck. |
| -Sama |
