Tutorials LightWave 3D Texturing 102: Gradients & External Parameters

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by Gregory Duquesne

Landscape Modeling

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Intothinair

Modeling
a landscape can be done in many different ways.
In this tutorial we will explore 2 ways to do
it: one using the SDTS loader, the other by using
procedural textures.

Both techniques rely on the
use of subdivision surfaces. To create the base
object that will be turned into the landscape:

Start Modeler.
From the top view use the box tool to create
a flat plane. Enter (1,1,0) for the size and
center it at (0,0,0).
Convert the polygon to a subdivision surface
using the Tab key.
Assign a surface to the polygon (q), name
it "Rocks".
Save the object.
Switch to Layout and load the object.
From the Objects Item Properties panel,
set the Display SubPatch Level to 20 for openGL
preview and the Render SubPatch Level to 100
for rendering. This will provide a larger number
of subdivisions needed to generate the landscape.

SDTS maps:

SDTS images are satellite measurements
of elevation maps, they give exact data about
the topology of wide areas that cover most of
the US map, they can be freely downloaded and
are available online.

[Tens de ter uma conta e sessão iniciada para poderes visualizar este link] or [Tens de ter uma conta e sessão iniciada para poderes visualizar este link]

The SDTS loader was created
as an image loader plugin by Marvin Landis. It
loads the elevations for each point and converts
them to floating point values between 0 and 1.
You can then use the image map as a displacement
texture to affect the geometry:

Go online to the above address. Select a
location from which you want get the elevation
map. Download the file. Now if you work on
Windows, you might have to rename the file
from "xxxx_tar.gz" to "xxxx.tar.gz", after
that you can extract the archive using WinZip.
From the Object Item Properties panel, Add
a Displacement Map to the object by clicking
on the T (Texture) button that's located on
the Deformations tab.
Load the SDTS image (it doesn't matter which
one you select, the loader will find the elevation
data).
Set the projection axis to Y.
Click on automatic sizing. Now you should
see the landscape in Layout.

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Dispmap

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Dispmap

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To set the lighting you can
use the LW_SunSpot plugin that will give you
the correct lighting conditions given the location
and the date and time:

Select the Light. Open the Motion Options
panel.
Add LW_SunSpot modifier, open its editor,
set the date and time.

Procedural maps:

Another easy way to create
a landscape is to use a procedural texture instead
of an image map as a displacement. The benefit
of doing so is that you can explore the procedural
texture, tweak the settings and find the place
you like most, which you can not really do with
an image map. One the interesting things about
procedural textures is that they are often based
on fractal techniques, which were themselves
inspired by the observation of mountains and
coastlines, so fractal textures are naturally
well suited for landscape modeling.

On the same scene, add a Null object in layout
Open the displacement texture editor (objects
properties, Deformations displacement map).
Change the layer type to procedural, set
the procedural type to "Crumple". Crumple is
a very good basis for mountains, though what
you should see is very noisy: peaks everywhere
with no real structure. That's because the
fractal dimension is wrong, this value is very
important when trying to simulate natural phenomena's
such as mountains, it can be translated as
a roughness parameter. We can set the fractal
dimension by adjusting the small power, this
sets the relative amplitude of increasing frequencies.
A value of 1 means that each frequency will
have the same amplitude resulting in a rather
noisy signal with lots of spikes, lower values
will make the signal smoother by attenuating
high frequencies. Set the Small Power to 0.3,
this seems to give pretty natural landscapes.
Set the reference object to "Null". Now that
we have done that we can move the object around
and visually explore the texture. This is also
a way to animate the texture, notice how the
texture evolves when moving the null on the
Y axis. What is happening there is that we
are slicing the texture with the XZ plane,
thus when moving along the Y axis we get a
different slice of the texture, creating this
interesting animation effect.

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Dispmap_2

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Dispmap_2

Landscape Surface Settings

For the surface settings, load
the scene Snowy_Mountain.lws.
From the Render Options panel, set "Enable VIPER" on
and render. This will allow us to work on the
surface with a direct preview on the rendered
image:
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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Mountain_preview

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Mountain_preview

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Open the surface editor, open
VIPER (in the options or F7), click on "Render" in
the VIPER window, you should now see the mountain.
Note that the preview does not look exactly like
the final render, this is because we are previewing
the surfaces, the effects of shadows, fog, pixel
filters, etc. are not taken into account for
surface previews.

We are going to recreate a
snowy rocks shader similar to the one used in
the introduction image, for that we will need
to create a color texture and a bump texture.
The bump is used as an additional layer of geometry:
it is adding the small details that the displacement
can not create considering the limits imposed
by the number of polygons that can be used for
the model. It is interesting to see how we can
model different levels of details with the same
tools: the shape of the mountain, the rocks on
the mountain, the distribution of mountains in
the scenery, everything obeys the same fractal
behavior

The Bump Texture:

Let's start with the bump channel.
On a snowy mountain, the bump will vary greatly
depending on the presence of snow: where the
snow sticks (that is where it's not too steep),
the rocks are not apparent and therefore the
bump (or roughness) is null. Of course where
we have rocks it is very steep and the bump/roughness
is high. So we have a simple parameter we can
use: we can filter the bump by the slope, that
will keep the flat areas smooth and flat and
make the steep areas rough and bumpy.

Open the Surface Editor and select the 'Rocky'
surface.
Add a texture to the Bump channel, set the
Layer Type to Procedural and the Procedural
Type to Crumple. Set the Texture Value to 300%
so that we have a strong effect.
Set its Scale to the following: ( 0.3, 0.1,
0.1 ).
Add a gradient layer. Set the parameter to
slope, set the blending mode to Alpha. Add
2 keys: one at 0.25, the other one at 0.5.
Set the value of the 2 first keys to 0. You
should have the following gradient:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Snow_bump_slopegrad

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Snow_bump_slopegrad2

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As you can see in the preview,
that makes the bump apparent on non flat areas
only, we can adjust this by just moving the keys
in the gradient. The gradient really acts like
a mask on the underlying texture. Now that we
have the bump, we just need to set the color.
In the surface editor, set the bump amplitude
to 0 % for the moment, so that we can work on
the color alone.

The Color Texture:
What we want to do here is to create is a strata
rock texture.

Add a texture to the Color channel, set the
Layer Type to Procedural and the Procedural
Type to Turbulence, set the Texture Color to
black.
Set the Scale coordinates to the following:
( 2.0, 0.1, 2.0). Set the texture to "World
coordinates". As you can see, this makes the
texture stretched in the XZ plane and compressed
along Y:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_base

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_base

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Add a Gradient layer, keep the Input Parameter
set to Previous Layer, create a ramp of color
in the brown tones to achieve something like
the sample below. What we did here is just
to remap the values created by the previous
layer with a color ramp. This is close to what
we want, but a strata rock texture in nature
would be much less regular. To simulate that
we can use a texture displacement layer:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_color

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_color

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Add a Procedural layer, Keep the Procedural
Type as Turbulence. Move it to the bottom of
the list, and set its Blending Mode to Texture
Displacement. Set the scale to ( 0.3, 0.3,
0.3 ). Here is what the Viper window should
show:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_disp100

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_disp100

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Obviously the perturbation is way too strong.
Adjust the layer opacity to 10%, that looks
much better now:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_disp10

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_disp10

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Now for the snow : Add a Gradient layer and
set the Input Parameter to Slope.
Set the first key to be white.
Add 2 keys: one at 0.25, the other at 0.5.
Set the alpha channel for the last key to 0
%. You should see this:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_snow

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Strata_snow

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Go back to the Surface Editor and set the
Bump channel amplitude to 100. We now have
the final surface with the effects of the bump
and color textures combined:

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<td> Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Mountain_complete

Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Mountain_complete

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Voila c'est fini !

Make a full render (F9), the
final image now also has the effect of fog using
both LightWave®'s standard fog and the ground
fog (Effects->Volumetrics).</td></tr></table>

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1 Tutorials LightWave 3D Texturing 102: Gradients & External Parameters Qua Jan 26, 2011 1:52 am

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