Dirt 2 - Making a realistic Wall with
Materials vs Geometry
This scene was a simple exercise in creating
realism through materials. Note that there
is only 3 rectangles and 1 cube in this
scene ! We could have cleaned up the junction
between grass and edge with a NURB surface
example scene: dirt/projects/dirtywall.r3d
There are several elements in this scene:
The wall, grass, downpipe and grass edge.
Lets examine each in turn and how we achived
This object has the most materials applied:
At the "back" is our first crack
- this is simply a bump image (Black and
White) of a crack. Note if we map consecutive
bumps to each other, the background must
be black as white is high, black is low.
We wanted the material to crack in, so we
have used a negative value to "invert"
Next is the brick photo by itself. This
is only a small section of a brick wall
made "Tilable" This is best achieved
in Photoshop by using the filter/offset
with 'wrap around' set, to see how a material
tiles. Using the stamp tool, you can make
a material tile properly.
Over the brick we have put a subtle noise.
to see the values used for the noise. This
adds a basic black and white noise on top
of the brick to give it a slightly dirty
appearance. Note we use the Scope parameter
of the parallel mapping object itself (Under
the Properties/spec tab) to give the noise
more or less effect. Currently set quite
On top of the brick we have added a stain;
vertical water stains that have dripped
down from the top of the brickwork. This
material is simply a scope material. The
scope channel uses a B+W image again, with
white designating the area of effect. Note
we can put any material or colour in this
material and the area of scope limits it
to this. In this material however, we have
simply used a color- hence the scope limits
the colour to the area of the scope image,
thus creating our vertical stains.
Then we have a simple brick bump. Note
we could just as easily have added the bump
with the brick material. We have used the
original bump material for the bump channel,
but ideally we would create a B+W bump material
to emphasise the areas of interest (The
Last is the Graphiti. Like our stain, the
graphiti is simply a scope material. The
white defines the area of colour, and creates
our graphiti. Note that any of these scope
materials can be moved freely around the
wall or duplicated to create more. Also,
we have set the FINITE tags under the parallel
mapping object. This limits the area of
effect for this material within the boundaries
set by the mapping object. Unless we wanted
to tile this graphiti, generally we should
use FINITE mappings for scope based objects.
This object was used to show the use of
the fade mapping channel. We could have
just as easily mapped this material onto
the brick wall using a scope instead of
This material has a fade and a colour channel
used. Note that we have also used a fade
constant (above). We set the fade as a constant
of 1 (white) then with the image mapped
to the fade channel, we use a SUBTRACT operator
to essentially "invert" the alpha.
We do this because RS3D uses White for transparent
and black for solid in FADE channels only.
Scope uses the opposite. Hence, we INVERT
our alpha channel by doing this. The texture
is a Targa, so the alpha is embedded into
the same texture. Hence, both the colour
and fade textures have the same image applied.
Under Bindings tab of the fade texture,
you can check that it is bound to alpha->fade.
An alpha JPG would have something like ColorR->fade.
This material is then parallel mapped to
the rectangle and repeated in one axis.
the alpha acts as a cookie cutter and actually
cuts the object itself (vs using a scope
which merely limits the material).
This baseplane is simple: it has a grass
texture parallel mapping tiled, then another
'Grit' material applied over that - essentially
simulating some sticks over the grass -
and then a duplicate copy of our Noise material
from the brick to simulate a bit of un-evenness.
This object is probably more complicated
than it needs to be - but shows a multiple
layering of scoped materials. Note these
materials make use of the scope - hence
we have not globally set the colour of the
object itself - hence the colour is derived
from the object properties/col tab. The
multiple scoped materials give a random
appearance to flaking paint - all 3 of which
are simply B+W scope maps and a color. We
then added our noise again to give it some