[vtkusers] volume rendering transfer functions

[Lisa Avila]

Yes - they are multiplied. The scalar opacity is an "opacity per length" 
value (where the length is the ScalarOpacityUnitDistance in 
vtkVolumeProperty). This is normalized for the step size before being used. 
The gradient opacity is a "modulation" value - given the gradient magnitude 
at a location, look up the opacity and multiply the scalar opacity for the 
ray segment by this.

Lisa


At 10:46 AM 4/9/2004, Charl P. Botha wrote:
>Sean McInerney wrote:
>
>>Thanks Charl,
>>   Always nice when something boils down so simply. Absolutely brilliant. 
>> Do you recall if this was within the volume mapper code?
>
>Have a look at the vtkVolumeRayCastCompositeFunction source.  Text 
>search/grep for "*= gradient_opacity". :)
>
>Regards,
>Charl
>
>--
>charl p. botha http://cpbotha.net/ http://visualisation.tudelft.nl/
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