8

Hair and Fur Modifier 513
Top: Hair Count=1000
Bottom: H air Count=9000
By default, Hair normalizes density to surface area;
that is, larger polygons receive more hairs than
smaller ones. If you edit the growth object in a
waythatchangesthepolygon-sizeratios,use
Reset
Rest
to adjust the hair distribution automatically.
Hair S egments—The number of seg ments per hair.
Default=8. Range=1 to 150.
This is equivalent to spline segments; with more
segments, curly hair looks more natural, but the
generated mesh object is larger. For perfectly
straight hair, set Hair Segments to 1.
Left: Hair Segments=5
Right: Hair Segments=60
Hair Pas ses—Sets the number of transparency
passes. Default=1. Range=1 to 20.
Hair’s
buffer render has a fairly novel way of
handling hair transparency. Instead of resolving
actual hair t ransparency, the hair is rendered
multiple times (as opaque hair) with different
random seeds. These buffers are then blended
together. As you increase the Hair Passes va lue, the
transparency (or wispiness) of the hair increases.
In addition, increasing the value increases the
actual number of rendered hairs as well, although
the apparent density, or fill, seems about the s a me
because of the additional transparency. Render
time also increases linearly.
Top: Hair Passes=1
Bottom: Hair Passes=4
Note: For best results when using the MR Prim
hair rendering method (see
Hair and Fur Render
Effect (page 3–216)
)withthementalrayrenderer,
be sure to set the Trace Depth > Max. Depth value
(see
Rendering Algorithms Rollout (mental ray
Renderer) (page 3–113)
) higher than the Hair
Passes value.
Density —The numeric value s ets the overall hair
density; that is, it acts as a percentage multiplier of
the Hair Count value. Default=100.0. Range=0.0
to 100.0.
Top: Density=100.0 + map
Bottom: Bitmap applied to Density map
This attribute is also mappable via the map button
to the right of the spinner. It lets you add a texture
map to cont rol the amount of hair. An area of