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1348 Chapter 16: Material Editor, Materials, and Maps
Bumpmappingusestheintensityofthemapto
affectthesurfaceofthematerial.Inthiscase,the
intensity affects the apparent bumpiness of the
surface: white areas protrude, and black areas
recede.
Use bump maps when you want to take the
smoothness off a surface, or to create an embossed
look. Keep in mind, however, that the depth effect
of a bump map is limited. If you want extreme
depth in a surface, you should use modeling
techniques instead. For example, the
Displace
modifier (page 1–608)
pushes surfaces or faces in
andoutbasedontheintensityofabitmapimage.
(
Displacement mapping (page 2–1352) is another
way to do emboss a surface.)
Grayscaleimagescanmakeeffectivebumpmaps.
Maps that shade b etween white and black generally
work better than maps w ith hard edges between
the white and black areas.
The bump map Amount adjusts the degree of
bumpiness. Higher values render as hig her relief;
lowvaluesrenderaslowrelief.
Thebumpsareasimulationcreatedbyperturbing
face normals before the object is rendered. Because
of this, bumps don’t appear on the silhouette of
bump-mapped objects.
Tip: If you render a bump-mapped material and
notice aliasing in the highlights, try turning on
supersampling (page 2–1302) and rendering again.
Note: Most controls on the Output rollout (p age
2–1430)
don’t affect bump mapping. Only the
Invert toggle is considered; it reverses the direction
of the bumps.
Procedure
To assign a bump map:
1.
Click the Map button labeled Bump.
The
Material/Map Browser (page 2–1256) is
displayed.
2. Cho ose from the list of map typ es (page
2–1426)
,andthenclickOK.
TheMaterialEditorisnowatthemaplevel,and
displays controls for the map parameters.
(If you choose Bitmap as the map type, you first
see a file dialog that lets you choose the image
file.)
3. Usethemapcontrolstosetupthemap.
Tip: To avoid aliasing caused by a 2D bump
map, go to the bump m ap’s Coordinates
rollout.SetBlurtobeintherange0.3to0.6,
and increase Blur Offset to be greate r than 0.0.
The default Blur and Blur Offset values work
well for mapping other material components,
but for bump mapping, lower Blur and higher
Blur Offset values give better results.
To remove a bump map from a material:
Tip:
You can disable the map without removing it.
Simply turn off the toggle immediately to the left
of the map button on the Special Effects rollout.
1. If the Material Editor is displaying the map
controls, click the
Type button (page 2–1293)
to display the Material/Map Browser. If the
mapcontrolsaren’tvisible,clicktheBumpmap
button to display them, and then click the Typ e
button.
2. In the Browser, choose NONE as the map type,
and then click OK.
The map is removed.