Snapshot & texture interpolation

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Snapshot & texture interpolation

Kannan U V
Hi,
I am rendering a visualization with slice from one volume data and
volume rendering from another volume data and I want to create a
snapshot of that visualization. I have couple of problems when I do
it.

1) When I use the snapshot utility I get the following figure with a
halo of background around the slice. Only different thing I am doing
in the visualization is setting the resolution of the manually using
the TCL interface.
2) In the visualization of the red slice below, there are rectangles
marked up with solid white lines. When rendering it appears dotted. I
guess it is an rendering artifact in the way interpolations are
handled in textures. How can I change that? Please let me know where I
can find a tutorial about the TCL interface to slicer.

Thanks,
Kannan

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Slicer99_0.png (515K) Download Attachment
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Re: Snapshot & texture interpolation

Kannan U V
The image artifact for the interpolation problem is in the attached figure.

Thanks,
Kannan

On Thu, Jan 13, 2011 at 11:48 AM, Kannan U V <[hidden email]> wrote:

> Hi,
> I am rendering a visualization with slice from one volume data and
> volume rendering from another volume data and I want to create a
> snapshot of that visualization. I have couple of problems when I do
> it.
>
> 1) When I use the snapshot utility I get the following figure with a
> halo of background around the slice. Only different thing I am doing
> in the visualization is setting the resolution of the manually using
> the TCL interface.
> 2) In the visualization of the red slice below, there are rectangles
> marked up with solid white lines. When rendering it appears dotted. I
> guess it is an rendering artifact in the way interpolations are
> handled in textures. How can I change that? Please let me know where I
> can find a tutorial about the TCL interface to slicer.
>
> Thanks,
> Kannan
>


--
Thanks,
Kannan

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InterpolationProblem (671K) Download Attachment
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Re: Snapshot & texture interpolation

pieper
Administrator
In reply to this post by Kannan U V
Hi Kannan -

What version of slicer and platform are you using?

I think what you are seeing is an artifact of the way opengl handles
texture mapping - historically, opengl required that textures be
provided with dimensions that are powers of 2 so VTK resamples the data
and that can result in the issue you see (has to do with the
transparency threshold being interpolated)

But on more recent versions of opengl and vtk, the power of 2
requirement was relaxed and these artifacts went away.  So there's a
chance that with an updated graphics driver or the latest version of
slicer these could to away. FWIW I don't see that kind of artifact on my
machine.

Regarding the tcl interface, pretty much the full API is available to
control.  So if you look at the doxygen and other developer resources on
slicer.org you can find hints on things to access via the console.

-Steve

On 01/13/2011 11:48 AM, Kannan U V wrote:

> Hi,
> I am rendering a visualization with slice from one volume data and
> volume rendering from another volume data and I want to create a
> snapshot of that visualization. I have couple of problems when I do
> it.
>
> 1) When I use the snapshot utility I get the following figure with a
> halo of background around the slice. Only different thing I am doing
> in the visualization is setting the resolution of the manually using
> the TCL interface.
> 2) In the visualization of the red slice below, there are rectangles
> marked up with solid white lines. When rendering it appears dotted. I
> guess it is an rendering artifact in the way interpolations are
> handled in textures. How can I change that? Please let me know where I
> can find a tutorial about the TCL interface to slicer.
>
> Thanks,
> Kannan
>
>
>
> _______________________________________________
> slicer-users mailing list
> [hidden email]
> http://massmail.spl.harvard.edu/mailman/listinfo/slicer-users
> To unsubscribe: send email to [hidden email] with unsubscribe as the subject
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