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1Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces Empty Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces Qua Jan 26, 2011 2:01 am

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by Leigh van der Byl
Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces Pixel_black


Hello everyone, and welcome to the all new and
improved Texturing For Dummies!
Some of you may have read these before, but
I have since re-edited them to be totally
LightWave® specific, and a little more
in-depth in terms of application.

Most of the images I will be
using are made from the content that comes with
LightWave®, so you can explore all these
options as I will demonstrate.

Before we go on, let me just
point out that under absolutely no circumstances are
you going to find any tutorials on how to make
tacky chrome surfaces or light blue glass in
this series. There is quite enough of that out
there already. Not that I think there is anything
wrong with those, it's just that those tutorials
will only get you so far, and when you are suddenly
faced with the challenge of texturing a photorealistic
shower attachment or elephant's toenail, they
are going to get you nowhere.

What I intend to do is to illustrate
exactly how to observe real life surfaces and
recreate them digitally. With all the frills.
And that means absolutely no tiled texture
maps!.
Basically, I am hoping that this can be a sort
of "texturing manual" for you when
you need to do your texturing - so if there is
anything in particular that you want to know
more about, let me know, and I will include in
an upcoming chapter.

Luckily for us LightWave® users,
we have a FANTASTIC surface editor with which
to work - in my opinion, the Surface Editor in
LightWave® has the greatest number of options
available for us to work with, with the least
amount of hassles. There are no surfaces that
you cannot somehow produce with a little know-how
and clever manipulation of its settings.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_A
Within LightWave®s Surface Editor, you
have all the tools at your fingertips to make
beautiful, believable photorealistic textures.
All you have to do is know what all
these options are!


Well, let's begin!

Observing the Aspects of Surfaces
In Real Life


If you wish to become a brilliant
texturing artist, the first thing you are going
to have to do is learn how to properly observe
surfaces in the world around you. You need to
look at things and, in your mind, break the surface
apart into its different aspects.

Look at a brick wall - study the
variations in colour, notice how the light is
broken up along it's surface, feel the groves,
scratches and bumps on the bricks themselves
as well as the grain of the cement between them.
Even take note of it's temperature - I know that
sounds strange, but that can become very important
when you are trying make people really believe
that the surface exists. People looking at your
textures must be able to imagine exactly how
it feels to touch, and the temperature of the
surface is definitely important, But that is
a detail that I will go into depth at a later
stage.

You need to begin looking at the
world around you in terms of the aspects that
you will recreate digitally. I know this may
sound really bizarre, but when I am driving to
work in the mornings (this usually being the
only time of day that I actually see the world
outside.), I often find myself looking at an
old garbage can on the side of the road, and
thinking "hmmmm. that can has an awesome diffusion
map on it" or looking at an old council truck
and thinking "what a cool specularity map that
has".

It is because I think like that,
that when I sit down to work and am given something
to texture, I can draw directly from my memory
and experience, because I do know offhand what
the diffusion of metal looks like, or how to
do really great rusty streaks on the side of
a truck.

Make an effort to break up things
you see into Colour, Diffuse, Luminosity, Specularity,
Glossiness, Reflection, Transparency and Refraction,
Translucency and Bump aspects. Some surface areas
also include Displacement, which is basically
a Bump map that actually alters the geometry,
but because it is then, technically, a geometric
property, I will not deal with it in too much
detail, as it doesn't really affect the other
surface attributes as such.

Observe how these different aspects
interact with each other - for instance, very
reflective transparent glass, isn't very reflective
and is less transparent where it is scratched
and where it has been dulled (by been handled
or by being wiped by a dirty cloth).

Now, in order to begin observing
all these aspects correctly, you need to have
a very good understanding of what each of these
are.

The Different Aspects Of Real
World Surfaces


Of course fully explaining every
one of these properties in great depth would
take too much time right now, so I am going to
give a very brief explanation of each of them
now, and then later on I will do a separate workshop
dealing with each of them individually.

Pictured below is the star of
the show for today - I pried this gorgeous little
skull out of the content that comes with LightWave® to
demonstrate how the different parts of texturing
work, and how each different aspect affects its
surface. Let's call him Frank.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_A

Now, although Frank looks pretty
fantastic already, I think that perhaps he should
have a makeover, just for the fun of it. Let's
see what we can do with him..
Colour

The first aspect of texturing!
Well, I guess this one is pretty self-explanatory.
All objects have colour. Although it is probably
the most basic of the surface attributes that
you will have to make when texturing something,
it is by no means an easy one to produce. Nothing
in real life has a constant perfect colour. Any
object has a colour which is uneven in places,
even if only slightly.

The colour map is usually the
best one to start off with, when beginning to
texture a new object, as it will give you an
excellent starting point for the feel of the
object. Be sure to add in loads of details for
added realism - things like faded areas, scratches,
smudges, blemishes, weathered marks - anything
that makes it look like it exists in this world.
Colour maps are generally the only image maps
that you will make that contain any actual colour,
as the other surface properties are best created
in shades of grey.

Okay, so lets add some colour
variations to Frank and see what happens... Firstly,
I've set all the other surface properties to
0%, so all you are seeing below is the raw colour
applied to the object.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_B

As you can see, the colour is
very important to place the details that you
need on the surface. These are just very simple
examples of colour maps for surfaces - for really
realistic recreations of things, you need to
study the object that you are making very closely
in order to ensure that all the necessary details
are included. Reference material when texturing
things is absolutely essential - always have
loads of reference pictures of the the kind of
surface you are trying to make, as well as actual
physical examples, if possible.

Obviously, because there are only
colour properties and nothing else assigned to
Frank at the moment, he is looking a little flat.
So let's explore some more options for getting
him looking a little more interesting...

Luminosity

This attribute determines whether or not an object
has any self-illumination properties, and how
strong they are. This is only used for things
like florescent lights, light bulbs, LED displays,
electronic billboards, lava, molten metal, and
so on.

Below, Frank seems to have transformed
briefly into a volcanic landscape!

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_C


A luminosity map works best in
conjunction with radiosity, so that the luminous
value can become translated during the render
process as a source of light, and will thus illuminate
objects around it slightly. Bear in mind that
your settings have to be rather high for this
effect to work best.

For added effect, it's often nice
to add an appropriate amount of glow to the surface.
You can enter in a glow value in the Glow Intensity
box under the Advanced tab in the surface editor.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_B
The Glow Intensity option in the Surface Editor


Note that in order for your object
to render with the glow you have assigned to
it, you need to enable it in Image Processing.
You can do that in Layout by going to Scene>Effects>Image
Processing
, and ticking the Enable Glow option.
You can also assign your overall glow intensity,
as well as set the glow radius (its size) in
pixels.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_C
You need to activate the Enable Glow option
to
render your surface with a glow


The glow option is cool for adding
a halo around a lightbulb, or a faint shimmer
around a magical crystal, and other things like
that. For more dramatic effects, such as the
haze of light from a streaming river of lava,
I would suggest actually using volumetric lighting,
as the glow will probably not be sufficient.

Diffuse

One of many great things about LightWave®s
Surface Editor - we have the option of real diffusion.
Firstly, let me dispel a common misconception
- diffusion is not colour! Diffusion is the attribute
of an object's surface that scatters light. It
determines the actual amount of light that is
reflected by the surface. In essence, it determines
how much of the surface's colour we'll see.

By diffusing an object, you limit
the amount of colour that is reflected back by
the light. This is completely different to simply
darkening the surface of the object itself. If
you were to darken the actual image used as a
colour map, you would see only see a change in
colour, but not a sense of colour depth. Colour
depth is created by scattering light across an
object's surface.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_D

Take a look at human skin and
you'll notice that it has a density. The colour
isn't a simple continuous shade but rather many
similar shades, created by scattered light. This
quality can not be made by a colour map alone,
as a colour map cannot give a surface the richness
that a diffuse map can. Obviously, having said
that, Diffuse and Colour go hand in hand. Diffusion
also works very closely in conjunction with Reflection,
which I will discuss in a moment.

Something to bear in mind when
using diffusion is that you need to lighten your
colour maps in order to compensate for the amount
of darkening that the diffusion will cause. For
instance, if your surface has a diffuse amount
of 80%, you should make all your colour maps
20% lighter than they would ordinarily appear
to be, so that when the surface becomes diffused,
these tones do not become desaturated or too
dark.

Using diffusion correctly ensures
that your surface does not become oversaturated
when it is illuminated by a light source. Surfaces
that have 100% diffusion tend to have large,
unsightly oversaturated hotspots where the light
hits them - lowering the diffuse amount appropriately
prevents this from happening. I will be going
into great depth about Diffusion in Part 3 of
this series.
Specularity And Glossiness

It is a shame that Specularity, an extremely
important aspect of a surface, is all too often
overlooked. In fact, I would say that Colour
and Specularity are the two most useful basic
surface attributes in determing the initial look
and feel of your surface. Below you can see that
Frank has now got a bit of specularity (as well
as some bump, to help define the surface, and
thus enhance the specularity a little) applied
to him:

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_E

The specularity of an object determines
how shiny it is and how light is broken up by
it's surface. Now, keeping in mind what I said
earlier about being aware of how people and weather
interact with and affect a surface, you make
use of a specular image to show how the world
has "made it's mark" on the object, so to speak.
Things like smudges from a cloth, fingerprints,
wetness, polishing, etc will all play a part
in determining what goes into the main specular
image.

Specularity works most closely with
three other surface properties - Glossiness,
Bump and Reflection.

Specularity in conjunction with
Glossiness determines how spread out or how tight
an area the light's "hotspot" becomes when it
come into contact with the surface. An object
with only a small difference between the specularity
amount and the glossiness amount have a very
small "hotspot", therefore they appear plastic-like;
whereas an object with a large difference between
the two will spread the light out over a much
wider area, therefore appearing more dull, like
metal (except chrome-plated metal, of course).

The moment you add any specular
amount to a surface, the Glossiness option becomes
activated, and you adjust this setting in order
to get the right balance of shininess.

Bump works hand in hand with specularity
in that generally parts of an object which protrude
more become more worn. And depending on what
the surface is, that will either increase or
decrease the specularity - wood, for instance,
generally becomes shinier when it is rubbed a
lot, whereas metal can become duller. Another
way in which bump and specularity work together
is in the case of scratches along a surface -
a scratch will tend to gather grime and dust,
and will therefore become very dull after a while.
A quick way of ensuring that your specularity
interacts nicely with the bump map, is by placing
a gradient into your specularity channel that
gets its input from the bump map, as shown below.
Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_D
You can use a gradient set
to Bump as its Intput Parameter to control the
specularity according to the height of the bump
map


The interaction between reflection
and specularity is pretty obvious - where a reflective
object has been, for instance, touched by a person,
oil from the fingertips gets left behind, and
makes the surface appear less reflective in that
area. Another example would be if you had to
texture a car's front windscreen, where it is
a cold night and the driver has wiped a cloth
along the glass to clear the mist on it, the
cloth leaves lines in the direction it has been
pulled across the surface - those streaks will
make the surface appear a lot less reflective
than parts that weren't touched by the cloth.
It is probably safe to say that there exists
no object in this world that is 100% reflective
all over it's surface, because sooner or later,
someone or something is going to touch it and
affect it's specularity, thereby affecting it's
reflection. There is a wide debate, however,
between the use of reflection and specularity.
A lot of people prefer to not use specularity,
and prefer instead to solely rely on reflection
to make their surfaces shine. I will explore
this debate further in Part 4 of this series.

You get two common kinds of specularity
- normal specularity, and anistropic specularity.
Normal is just plain straight specularity, whereas
anistropic specularity is used for surfaces which
has extremely tiny bumps along it's surface.
You can implement Anisotropic reflections by
using LightWave®s BRDF shader, but I will
get more into detail about that when I deal with
specularity at a later stage, in Part 4 of this
series.

Reflection

Another pretty self explanatory
property, reflection determines how reflective
an object is and in what areas it is reflective.
Below, Frank has become chrome plated...

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_F

As previously mentioned in the
paragraph on specularity, the reflection map
should vary along the surface according to how
it has been interacted with. This attribute is
sadly often overused - a huge giveaway that an
object is CG is often due to the fact that the
texture artist has made it too reflective. That
is not to say that reflectivity is not a common
property - in fact, most things which are in
any way shiny, are slightly reflective too. Although
reflectivity is not to be confused with the effect
that radiosity has on objects, where the surface
of one object can pick up small traces of the
colour surrounding it due to bounced light. You
should attempt to create this effect with reflection,
as your surfaces will just end up looking wrong.

The kind of reflection that an object has also
differs greatly - a mirror, for instance, produces
a perfect reflection where it is clean, whereas
steel, plastic, scratched Perspex, most liquids,
etc, have blurred reflections. LightWave® 7.0
(and onwards) has a blur option for reflection
- use it. All too often, you see horrible
renders of perfectly reflective kettles and such,
when the reflection should have been blurred.
When working with reflection,
something very important to bear in mind is it's
relationship with Diffusion. As a general rule
of thumb, the more reflective and object is,
the lower its diffusion
. This is because
the more an object reflects, the less of it's
own colour we can see. However, I will discuss
this relationship in greater depth at a in Part
3 and Part 4 of this series
Transparency and Refraction
Transparency is not Opacity. It is, in fact,
the opposite. Transparency determines how "see-through" an
object is (whereas Opacity determines how opaque
it is. An object which is 0% percent opaque will
generally disappear out of a scene, whereas an
object with 100% transparency will just be completely
see-through, yet still visible). Obviously, things
like glass, Perspex, liquids, crystal, etc have
varying degrees of transparency.

Transparency is also affected
quite a bit by the specularity of an object -
especially in the case of oily fingerprints left
on a surface - obviously these areas are not
going to be as transparent as the surrounding
areas that have not been touched.

Transparency has a special relationship
with Reflection, called the Fresnel Effect. This
effect is basically the variation of transparency
according to the angle at which you view it.
An example of this is if you see a lake from
a far off distance, it appears very reflective,
yet the closer to come to it, the more transparent
it appears. This effect of becoming less reflective
and more transparent increases as the angle at
which you see it increases. You can implement
this effect by using LightWave®s Fresnel
Shader, or by using opposing gradients in your
Reflection and Transparency channels. I will
discuss the Fresnel Effect in the upcoming chapter
on Reflection.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_G

Most substances which are transparent,
refract light. Refraction is the bending of light
through transparent bodies. This causes the effect
of, for instance, if you have a scene with a
glass of water in it, when you look at objects
through the glass of water the objects you see
are warped. Different substances have different
refraction amounts, and a table of these amounts
can be obtained almost anywhere - however, to
make things easy, you will find a handy Index
Table inside your LightWave® manual.

The higher the refraction amount,
the more light is bent as it travels through
it. Refraction amounts in reality do not exceed
2.0.

In the picture above, Frank has
a refraction index of 1.6 - as you can see, this
results in a rather drastic distortion of the
surface behind him.

Translucency

Translucency is the ability for
an object to be backlit without being transparent.
Take for instance, a curtain - when a light is
shone through it, you can see things moving behind
it, even though it is not transparent. In reality,
just about everything, with the exception of
metal and wood, has some degree of translucency.
This property can be extremely useful for skin,
in particular, so that if a bright light is shone
onto it, you can catch a glimpse of the veins
which run just below the surface.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_H

In the picture above, I have placed
a point light with a short falloff inside Franks
head, which is revealing the translucency map
of veins that I have placed on him. As you can
see, where the light shines through, the veins
are visible because they are getting in the way
of the beams of light.

Translucency works best when combined with a
calculation called Sub Surface Scattering, which
is a property that basically allows light to
enter the surface of an object, bounce around
inside the surface, and then leave it at a different
angle to that in which it entered. Translucency
and Sub Surface Scattering are extremely important,
especially for surfaces such as skin and fabric,
where they should always be used. LightWave®,
unfortunately, does not yet have built-in Sub
Surface Scattering, but there are a number of
plugins available that you can use in the meantime.

It's probably safe to say that
just about everything in this world is translucent
to some degree, so it's a pretty important thing
to keep in mind.

Bump

The most commonly-used attribute
next to Colour. Everyone knows what a bump map
is. Although, I must stress that a bump map should
never be used as a compromise for necessary geometry.
Bump maps should only be used for minor things
like scratches, small dents, grooves, small carvings,
minor variations in relief, and grain. Never
ever
use a bump to create something that
should actually be modelled. The reason for this
is that as soon as you get close to a bump map,
it becomes obvious that the objects surface relief
is actually flat.

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_frank_I

An alternative to bump mapping
is displacement mapping - displacement
using textures is similar to bump mapping, except
it actually deforms the objects surface according
to its settings. To use displacement in LightWave®,
you can make go to your Object Settings in Layout,
and activate the Displacement option under Deformations
tab (see Figure B).

Tutorials LightWave 3D Texturing for Dummies Part 1 An Introduction to the Aspects of Real World Surfaces T4dpart1_E
Activating the Bump Displacement
option in
your object properties


A Note On Making Your Own Texture
Maps


Something that is extremely important
when making your own texture image maps, is the
size of the actual image you make. In order to
determine what size you should make it, you need
to know what the final rendered frame size of
the animation is going to be.

Once you know what the final size
is, then you can work out the size of your texture
map as follows:

Take the maximum width that the
texture map can appear on the screen (in pixels)
and multiply it by two. Use this pixel size as
the size of your image map, if you want to ensure
that your textures do not become blurry or pixellated
when viewed up close.

For example, the most common frame
size when rendering for television is 720 pixels
X 576 pixels (PAL D1), so if you were to make
a texture image for an object that will be viewed
right up close in the frame, then the width of
your texture map should not be less than 1440
pixels.

I personally usually work with
square images, as I almost always work with UV
Unwrapping, so my images are generally at least
1440 x 1440 pixels. It's usually safe to leave
the image at 72 Dpi, as this is the resolution
that monitors and televisions display at.

Of course, the drawback to this
is that these kinds of file sizes for image maps
do slow down the rendering process quite a bit,
but on the other hand, you know they will hold
close-up. So if you have a job that is going
to end up on IMAX, you had better make sure your
computer can handle 4000 x 4000 pixel images..

Another important thing to know
and understand is how to make greyscale textures
correctly. As you know, greyscale images are
the best method of making maps for all the properties
apart from colour. In order to decide what shades
of grey to use, you need to first decide on an
overall percentage value for the overall channel
- for instance, if you are wanting to make your
specularity map, and your overall amount is 12%,
then start off by making your image 12% grey.
You can do this in Adobe Photoshop® by opening
the Colour palette and entering in a value of
12% into the B radio button where is says HSB,
above the RGB options. This ensures that
once you load your image map into the specularity
slot, your map will not alter your overall amount
except for the areas that you have worked more
detail into. Using this method ensures that nothing
unpredictable will happen, and gives you this
greatest control over maintaining overall amounts
remain the same.

That pretty much wraps up Part
1 of this series! I hope that have learnt something,
and that you feel more confident about approaching
these different options in the Surface Editor
in future. Obviously, this was only a very brief
introduction to each of these attributes, but
it is only an introduction, after all.
Stay tuned for more chapters in this series,
when we will explore each of these in great depth,
and I will be demonstrating how to make the most
of them, and how to create great textures for
each...
By Leigh van der Byl
[Tens de ter uma conta e sessão iniciada para poderes visualizar este link]

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