#!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 
