#!F-adobe-helvetica-medium-r-normal--18*
#!N
#!N #!Rcvolrnd
Coloring Objects for Volume Rendering #!N #!N #!N The volume renderer
interprets colors and opacities as values per unit distance. Thus the
amount of color and degree of attenuation seen in an image
object is determined in part by the extent of the object's
volume. The Color, AutoColor, and AutoGrayScale modules attach "color multiplier" and
"opacity multiplier" attributes to the object so that colors and opacities
will be appropriate to the volume, while maintaining "color" and "opacity"
components that range from 0 to 1 (so that objects derived
from the colored volume, such as glyphs and boundaries, are colored
correctly). See #!Lrendmdl,dxall1133 h Rendering Model #!EL in IBM Visualization Data Explorer Programmer's Reference. #!N
#!N These attributes adjust the colors and opacities to values that
should be "appropriate" for the object being colored. However, if the
simple heuristics used by these modules to compute the attribute values
are not producing the desired colors and opacities, you have two
alternatives. #!N #!I0 #!N #!F-adobe-times-medium-r-normal--18* #!N #!N #!I30 #!N o One
is to modify the result by changing the multiplier values of
the color and opacity attributes: #!N #!I0 #!N #!F-adobe-times-medium-r-normal--18* #!N #!N
#!I30 #!N 1. extract the "color multiplier" and "opacity multiplier" with
the Attribute module; #!N #!I30 #!N 2. modify them with the
Compute module; and #!N #!I30 #!N 3. replace them in the
object with the Options module. #!N #!I0 #!N #!EF #!N #!N
#!I30 #!N o A second is to multiply the values in
the "color" or "opacities" component: #!N #!I0 #!N #!F-adobe-times-medium-r-normal--18* #!N #!N
#!I30 #!N 1. mark the component ("colors" or "opacities") with the
Mark module; #!N #!I30 #!N 2. modify the values with the
Compute module; and #!N #!I30 #!N 3. "unmark" them with the
Unmark module to return them to the appropriate component. #!N #!I0
#!N #!EF #!N #!N #!I0 #!N #!EF #!N #!N #!N Only
the first of these methods should be used for "delayed" colors.
#!N #!N Finally, if you color a group of volumes and
the resulting image is black, the reason is that the current
renderer does not support coincident volumes. #!N #!N #!T,1,161,321,646 #!F-adobe-times-bold-r-normal--18* #!N
TAB Attribute TAB Type TAB Description #!EF #!N TAB color multiplier
TAB scalar TAB Multiplies values in the "color" component #!N TAB
opacity multiplier TAB scalar TAB Multiplies values in the "opacity" component
#!N #!N #!N #!F-adobe-times-medium-i-normal--18* Next Topic #!EF #!N #!N #!Lshading,dxall821 h Shading #!EL #!N
#!F-adobe-times-medium-i-normal--18* #!N
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