Building Convincing Terrain Materials in Bryce
going to use a three-texture material. That means that the
alpha channel for Texture C will be used to combine Textures
A & B. We'll start by building Texture A.
Open the material lab and select Texture A for the Diffuse
color and the bump height. Also knock the Ambience down to
0 while you're at it. Now click the second top bottom to take
Texture A into the Deep Texture Editor.
Initially, we're just concerned with how the Altitude and
Slope filters affect the combination of the various components,
so we're just going to use color before we start applying
Click the "3" in the top left to turn on all three components
and set both blending modes to Average.
For all three components, set the color mode to "RGB" and
"Linear Interpol3" and the Noise Type to "None". Now disable
the second two components for now.
2 - COPPING AN ALTITUDE
we're going to start playing around with the filters. Open
the filter dialog and make sure Component 1 is selected. Select
X(a*altitude+b) as the filter type. With this filter the "a"
value controls the abruptness of the change while the "b"
value controls the height at which it starts. Generally, if
your "a" value is positive, then your "b" should be negative
and vise versa. A positive "a" moves your color change and
noise down from the top, while a negative value moves it up
from the bottom.
For my purposes I selected an "a" value of approximately 3.6
and a "b" of about -0.83. I also use bright, highly contrasting
colors to check the height and slope variations more easily.
I came up with something that looks like the picture.
3 - HITTING THE SLOPES
we'll use the Slope filter for the second component. Enable
the second component and select the X(a*slope+b) filter. Again,
the "a" value controls the abruptness of the change while
the "b" controls the level of slope at which the noise starts.
Allegedly, with a positive "a" value, you can place noise
on the vertical surfaces, but I'm still trying to get that
to work like it says in the manual. So I always use a negative
value to place noise on the horizontal surfaces.
For this material, I used a "a" value of about -3.15 and a
"b"value of about 1.84. Again using highly contrasting colors,
I end up with something like the picture.
it's time to make some noise! (Sorry....). Time to choose
the noise type that will actually give us our texture. There
are quite a few that are appropriate for natural rock, like
RND Continuous, RND Linear, RND Saw, Turbulence and Fractal.
Stuff like Stucco Noise and Stone Cliff are good alpha channels
for combining textures, but I don't think they make good textures
The Vornoi noise types also make good rock textures.
Textures for this sort of work usually require high frequency
settings, anywhere from 300% and up. Keep the octave settings
low, from 0 to 2. Anything more and your texture gets too
muted. All noise should be set for 3D, unless you're trying
for layered rock appearance.
I also tend to avoid using Phase when building these textures.
They are already complex enough with adding more rendering
Select different noise and frequency settings for both components
1 and 2. Also, enable component 3 and set a different noise
and frequency for it. Component 3 does not get an altitude
or slope, as this component fills in the gaps not covered
by 1 or 2.
Also, be careful about changing the texture frequency in the
material lab, especially with altitude filters. The texture
frequency will affect the starting height of the noise. This
is is another way of controlling your altitude changes, but
Exit the deep texture editor and set your bump height to something
like 30. At this we point we get the image in the last picture.
Not exactly "convincing" at this point, but it certainly has
for now we're going to stick Texture A in an unused channel,
like Ambient Color and select Texture B for Diffuse and Bump.
Repeat the steps above, but throw in a little variety. Change
the order of components by doing the slope texture or the
all-over texture first. Invert the values for the altitude
filter so the noise comes from the opposite direction. Go
wild and experiment.
the time to build our alpha channel for Texture C. In the
material lab, CTRL-Click (I believe that's Command-Click for
Mac users) on the Texture C button for Diffuse Color and Bump
Height, activating all three textures, using the C as an Alpha
channel. Now take texture C into the Deep Texture Editor.
The same noise types you used for your color and bump textures
will work here, in addition to Stucco Noise and Stone Cliff.
Generally, noise in the alpha channel should be low octave,
lower frequency and not heavily filtered. You're looking for
high contrast. I usually use three components, using Blend
Altitude and Blend Slope as my blending modes. This varies
the manner in which the textures combine according to both
height and slope.
Also make sure that alpha output is enabled for your components,
of course. Bump and Color are irrelevant.
now it's time to take those wild colors we started with and
replace them with the color we actually want to use. For my
material, I'm aiming for a more desert-like rock formation,
so I'm going to stick with the sandy yellows, tans, and pinks,
with a dark brown or gold thrown in for "character."
Work through both textures, replacing your colors with more
"natural" colors that suit the terrain you're trying to create.
You might wind up with something like this.