Autodesk LIGHTSCAPE, Manual

Page: 124 / 362

Using Materials 7
116
Lightscape
6.
If the texture image has a specific size, for exam-
ple, a ceiling tile or a piece of a brick wall, enable
Fixed Size, and then enter the width and height in
the appropriate boxes.
7.
To combine the texture image with the color
specified on the Color panel, enable Blend.
8.
To use the texture’s alpha channel to modify the
surface transparency, enable Cutout.
9.
Click Apply to update the material definition.
The texture appears on any surfaces that use the
material.
Note: If textures are not displayed, click the
Textures button on the Display toolbar, or
choose Display | Textures.
Brightness
The texture brightness controls the brightness of the
texture as it appears in the final display and
rendering. It also controls the amount and color of
the light that the material reflects into the environ-
ment. Ideally, you should set the brightness of the
texture so that the Average Reflectance is within a
valid range for the type of material being defined. If
the texture brightness you want is outside the recom-
mended range, you should use the Reflectance Scale
and Color Bleed Scale on the Physics page to bring
these values into the recommended range.
Note: If the texture map you are using has large
areas of contrasting colors (for example, wide
yellow and blue stripes), then you should also set
the maximum reflectance within the valid range. If
the texture is more homogeneous (for example
marble or granite), then the average reflectance is
more significant.
Filtering Method
Lightscape uses two different types of filtering with
textures to compensate for discrepancies between
the actual image size and the image size as rendered
in the scene: Minimize Filter and Magnify Filter.
For each filter, several options are available. The
main effect of these filtering options is to blur the
texture. Blurring a texture is important when the
texture contains a lot of small, sharp features. A
small amount of blurring may be enough for a static
image, but animations usually require more. The
following tables list the options in order of
increasing blurriness.
Minimize filter is used when several pixels in the
texture cover the same pixel in the image.
Magnify filter is used when one pixel in the texture
covers more than one pixel on the screen.
Select: To:
Point Point sample the texture.
Linear Bilinearly interpolate the value
based on the four closest texture
pixels.
Point MM Point sample the closest level in
the MIP map for the texture.
Linear MM Linearly interpolate between
point samples from the two clos-
est levels in the MIP map.
Bilinear MM Bilinearly interpolate between the
four closest pixels at the closest
level in the MIP map.
Trilinear MM Trilinearly interpolate between
the four closest pixels on each of
the two closest MIP map levels.
Select: To:
Point Point sample the texture.