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Re: IsoSurface [message #39803 is a reply to message #39727]

Thu, 10 June 2004 08:46

David Fanning
Messages: 11724
Registered: August 2001

Senior Member

Aleks writes:

> Previously I used MatLab to combine slices of data and construct 3D
> models. My advisor chose to switch to IDL because of its "powerfull"
> features. 81 came from the number of slices I have. I'm not really
> sure what you mean by range of my values?

When you use Shade_Volume you are trying to create
a 3D contour of your data at some "value". If your
data values range from 100 to 200 and you contour
at 81, and look for the values "lower" than the
contour value, you are not likely to see much in
your plot. :-)

So, in the above example, if your data ranges in
value from 100 to 200, setting a contour level of
150 might be reasonable. The contour level should
be set based on the data values in the volume, not
the number of frames in the volume.

One way to see what range of data values you have is
to plot a histogram of the data values in the volume:

IDL> Plot, Histogram(vol)

You might see some likely looking peaks in the
histogram. Just above or below, or perhaps right
in the middle of a peak might be an appropriate
place to choose a contouring value for a 3D contour.

For a quick test to see if your contouring value is
"reasonable" you might pick something between the
minimum and maximum of the data:

IDL> Print, Min(vol), Max(vol)

Cheers,

David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/

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[Message index]

		IsoSurface By: siliconcube on Wed, 09 June 2004 14:44
		Re: IsoSurface By: Karl Schultz on Fri, 11 June 2004 06:47
		Re: IsoSurface By: siliconcube on Thu, 10 June 2004 18:41
		Re: IsoSurface By: David Fanning on Thu, 10 June 2004 10:57
		Re: IsoSurface By: David Fanning on Thu, 10 June 2004 08:48
		Re: IsoSurface By: David Fanning on Thu, 10 June 2004 08:46

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