| Re: Basics of SHADE_VOLUME [message #43358] |
Thu, 07 April 2005 14:41 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Leslie Welser writes:
> Actually, I don't think your 3-d scatter plot will work for me in this
> case (although I have used it before on another project, and it worked
> great!). The reason is that what I have is actually a 3-d array which
> represents a wavefunction in space, phi=dblarr(192,192,192). It is 3-d
> because at each {x,y,z} point, there is a magnitude for phi. So I
> guess the problem is really that I'm trying to represent a 4-d surface
> (3 dimensions for the x,y,z and 1 for the actual value of the array).
> I thought that using shade_volume would work for this, since it accepts
> a 3-d array as input. But the result looks about how you described it.
> I noticed that on your website, you have an example (MRI images) where
> you said to choose an isosurface of 50 and then you said that "the
> surface will enclose the volume values greater than 50". That's where
> I got the crazy idea to set the isosurface value as the minimum value
> of my dataset. But I think there is still something that I'm
> missing....
Well, I'm still unclear what it is you hope to
visualize, too. How about putting the volume into
something like SLICE3? Then you could look at slices
through the volume. Or, you could treat this as we
do with medical image volumes and look at the three
orthogonal slices in three separate windows.
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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| Re: Basics of SHADE_VOLUME [message #43359 is a reply to message #43358] |
Thu, 07 April 2005 14:22  |
Leslie Welser
Messages: 11
Registered: March 2005
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Junior Member |
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Actually, I don't think your 3-d scatter plot will work for me in this
case (although I have used it before on another project, and it worked
great!). The reason is that what I have is actually a 3-d array which
represents a wavefunction in space, phi=dblarr(192,192,192). It is 3-d
because at each {x,y,z} point, there is a magnitude for phi. So I
guess the problem is really that I'm trying to represent a 4-d surface
(3 dimensions for the x,y,z and 1 for the actual value of the array).
I thought that using shade_volume would work for this, since it accepts
a 3-d array as input. But the result looks about how you described it.
I noticed that on your website, you have an example (MRI images) where
you said to choose an isosurface of 50 and then you said that "the
surface will enclose the volume values greater than 50". That's where
I got the crazy idea to set the isosurface value as the minimum value
of my dataset. But I think there is still something that I'm
missing....
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| Re: Basics of SHADE_VOLUME [message #43366 is a reply to message #43359] |
Thu, 07 April 2005 12:44 |
David Fanning
Messages: 11724
Registered: August 2001
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Senior Member |
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Leslie Welser writes:
> Can someone describe to me the basics of using SHADE_VOLUME and
> POLYSHADE (in direct graphics)? I have a 3-d array which is
> (192,192,192), and I thought that using shade_volume would allow me to
> display the x-y-z grid along the 3 axes and then the magnitude of each
> particular point could be displayed as a color.
No, not even close, really. Shade_Volume generally
produces something that looks more like what a forensic
anthropologist would come up with if he discovered a
7 million old jaw bone in the desert and wanted a head
to go with it, than what you describe.
> What I'm confused
> about is the isosurface I should choose.
I'm confused about what it is you really want to plot.
It sounds more like a 3D scatter plot to me. Here is an
example of one of those. Is this what you had in mind?
http://www.dfanning.com/tips/scatter3d.html
Cheers,
David
--
David Fanning, Ph.D.
Fanning Software Consulting, Inc.
Coyote's Guide to IDL Programming: http://www.dfanning.com/
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