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There are a lot of vtk users who do volume visualization. I do
<BR>this myself for data collected with microtomography. There is
a
<BR>characteristic of the reconstructed data which I don't understand.
<BR>It's this: there are a lot of negative values in the data.
I've
<BR>attached a histogram which shows this. The histogram is symmetric
<BR>which suggests that the negative values are meaningful. I've
also
<BR>attached a picture of one of the slices with level=.2 and
<BR>window=1.4 using the units on the historgram scale.
<P>Is anyone familiar with the occurence of negative values and what
<BR>to do with them ? I know that the negative values need to be
<BR>eliminated to use volume rendering. In the past I've set them
<BR>to be 0 but I'm not sure this is correct.
<P>Thanks in advance,
<BR>Dave
<PRE>--
David E Jones
Du Pont Central Research
Experimental Station, Bldg 320
Wilmington, DE 19880-0320</PRE>
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