[vtkusers] transfer functions

[Lisa Avila]

To create a transfer function that will show something you need to 
understand the distribution of the scalar values in your data set. You 
could simply use the scalar range and create a ramp between these two 
values, but if these are singular extreme values then this will not work 
well. Instead, you can walk through the data looking at all scalar values 
and build a histogram (vtkImageAccumulate will do this for you). Then you 
construct your transfer function using the information in the histogram - 
for example, a ramp from 0 to 1 starting at a scalar value that is above 
20% of the data, and stops at a scalar value above 80% of the data. The 
exact function you want to use would really depend on you application area.

Lisa



At 12:30 PM 10/26/2005, A D wrote:
>Does anyone know any vtk functions to determine the points in the data
>set where the highest and lowest values occur?  I really need some help
>with this, so please post anything you might know.
>Thanks
>A D
>
>On Mon, 2005-10-24 at 11:12 -0500, A D wrote:
> > Can anyone help me figure out an algorithm in python (or any language
> > really) for formulating a generic/general transfer function?  It doesn't
> > have to be perfect, just as long as it shows something on most data
> > sets.  If you don't have a specific algorithm can you point me to some
> > references on creating general functions?
> > Thanks
> > A D
> >
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