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WEATHERING YOUR 3D ART
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Using 2D applications,
like Photoshop and Paint Shop pro, you can add grunge, age
etc to 3dDtextures, as well as paint of course :)
In 3D Applications, you can apply these "weathered"
textures, as well as create your own effects inside the
apps themselves: dirt mapping.
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1) UNDERSTANDING "WEATHERING"
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Real world surfaces of objects
are rarely ever, clean and perfect. This is vital to
note, as it's part of what makes things look "real".
Remember, in digital art, your goal is to trick the
viewer into making what you make believable or intriguing.
You have to "con" the eye of the audience
into accepting something as real. Sometimes that may
actually mean making something that you know is odd,
but the end result is good!
Thus, "grunge" is GOOD!! ;)
It's vital to achieving realistic looking objects.
Surfaces get affected by several factors:
- Staining. This may come from dripping water, of
spattered mud, or spilled materials.
- Sun bleaching. Over time, the UV rays and heat from
the Sun bleaches and fades colours.
- Physical damage. Corners of objects get hit, surfaces
get scratched, dented and parts broken.
- Add ons. Someone may slap a poster on a wall, another
layer of paint etc.
- Irregularity. Paint jobs, wood etc are rarely perfect
and will have variance. It's especially important
to remember this about historical or hand made items,
as they don't have perfect manufacturing standards!
;)
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2) EXAMPLE OF WEATHERING
A COPPER SPHERE
Note how the sphere on the right has smears and greenish
verdigris. Not perfect yet, but still much more realistic
than the "perfect" sphere to the right (which
I added some blotchiness to anyway, previously, as pure
copper is very unbelievable in most scenes).
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3) WEATHERING TEXTURES IN PHOTOSHOP
ETC
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2D Textures made for 3D objects in Photoshop,
Paint Shop Pro etc, can of course, and should be, weathered.
Methods for adding weathering to an image:
- Brushes. You can find lot of brushes specifically for
grunge. Careful use of them can easily add staining etc
to a texture, as they are designed to look like such features.
- Smearing, blurring etc of paint. You can paint some
shapes, then use Gaussian Blur to soften it, Motion Blur
to smear it on one direction (great for water staining
dripping down a wall etc). Or use the "Liquify"
tool (Photoshop) or Warp Brush (Paint Shop pro), to distort
the texture itself. That's great for making things not
so perfect and repetitive. Radial Blur can make dirt or
weathering look like it's spread out from a source, say
an exhaust or bullet strike.
- Use varied bits of effects on different layers with
different layer settings. One layer maybe in Soft Light,
another on Multiply. You can actually paint weahteirng
in grey on a new layer, set it to multiply and ti will
darken the original texture. I often make layers for "dirt"
and "scratches", and "edge highlights".
- Plugins. Some Photoshop Plugins can be good for adding
weathering. A very good plugin of that type is "Machine
Wash", by "Mister Retro".
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WEATHERING #1
- With this image, I started with 50% grey fill.
- Then in a selected rectangle to the left, I chose a
darker grey, used the FIll tool, but set a Pattern, rather
than the normal "Fore Ground Colour". This gives
an interesting textured, partially transparent fill over
the base grey.
- Next, in another rectangle more to the right, I repeated
this fill, and applied the Radial Blur filter, to show
how it smears things out in a way reminiscent of an explosion
pattern.
- In the final, furthest right area, I used some specific
Grunge brushes in Photoshop.
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WEATHERING #2
- In this image, over a sandy brown colour, on the left,
I opened a new layer, and with a darkish grey colour and
normal paint brush, I painted in some strokes, and set
the layer to "Overlay". This made the grey alter
the underlying brown, making it darker. This is a nice
trick to add grunging you can alter at will, without messing
up the underlying image, as it's on it's own layer! It
doesn't add colour though.
- In the middle I used a "Machine Wash" plugin,
choosing a lighter brown colour for the effect, and a
darker slightly greenish one too. The result is an interesting,
natural-looking effect.
- On the right side, I used a large grunge brush, with
a grey colour, but set to "Color Dodge", which
makes it greatly lighten the colour, giving a distressed,
sun-bleached look.
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Now, I'm not going to explain to you HOW to
make and paint weathering in 2D, beyond this, it's up to
you! Look at real objects for reference, it's largely learning
for yourself :)
This is, IMHO, one of the best tutorials on
weather painting itself, on the Net, by James
O'Donnell
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4) WEATHEIRNG IN 3D
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In your 3D app, you can apply
the weathered textures you've made in 2D. You can also
use many 3D apps material systems to add weathering .
I've explained how to do this in Vue, in a previous tutorial:
"Dirt Maps in Vue".
Basically, you can mix two materials, or overlay
them, or the like, depending on how your app works, with
the idea to add a dirty, weathered, but largely transparent
material, over the main material, to make it look dirty
and real.
The big advantage to using "dirt
maps" and procedural or mixed materials to create
dirt, rather than just a single image, is that you can
vary the dirt at will, thus using the same material, you
can make it very dirty, or covered in green slime, or
ornage rust etc.
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SHIP WITH WEATHERING
Here, weathering has been applied in different
ways.
- The metalwork and wood panelling has an overlayed
procedural material, giving random dirty looking marks.
- The turret at the rear has two materials: one shiny
steel, the other rusty steel, and they blend together
using a procedural function, to make the bottom dirty,
but not the top.
- The hull has a special function driving the dirt:
it's a mix of a random procedural and an image based
on the UVmap of the model which let me place dirt precisely.
The random function adds convincing natural touches.
- The sails are painted textures. I used two layers
to make the image: base pale tan, then over the top
a layer with a very large texture with darker tan-brown
applied. Then using layer maskes I ate away much of
the top layer, leaving darker areas near the edges,
which I left thicker near the places where the sail
is tied down.
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SHIP WITHOUT WEATHERING
The weathering has largely been removed (except the sails),
and you can see the difference.
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4) ADJUSTING A 3D TEXTURE
TO MAKE IT LOOK MORE REALISTIC
Here, I start with a basic procedural material
in Vue, and try to get it more realistic. To do so, I
went nad looked at pictures of actual bronze and copper.
From them I got correct colours using the Photoshop "Eye
Dropper" tool, and tweaked away, to get a roughly
decent weathered bronze.
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ORIGINAL MATERIAL
It's not very realistic, is it? ;) Corroded
metal like that would have more staining. Verdigris is
a pale greenish grey, and it builds up on a surface
as it forms crusts, not into the metal.
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FIRST TWEAKING
Here, the colour is more like old bronze,
actually setting the material colour in Vue to match colours
from pictures. Areas of verdigris though are *not* shiny,
it's a chalky material, so it needs more work.
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FINAL MATERIAL
It's sitll not perfect but a LOT better than
it was :) The verdigrisis the right colour, and sticks
out of the metal. The bronze has a lto of patina, but
it too lightfor "odl" bronze, it's nice for
recent, but corroded bronze though. To make it older,
it's very simple ot merely darken down the colour driving
the bronze.
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I hope you find this of use! :)
Silverblade,© 2008
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