[vtkusers] Texture Mapping Image Quality

[Patrick Lowry]

David:

VTK is subsampling the image.  Even for an image of less than 1000x1000 
pixels, it resamples to a power of two (as the documentation says).  For 
larger images it must resample it much more.

Are we stuck with this or are there additional settings that allow bigger 
image sizes?  It seems that large memory capacity, both on the mother board 
and on the video card (128mb) would allow larger images.

Thanks,
Patrick

At 02:10 PM 8/30/2004, you wrote:
>Hi Patrick,
>
>VTK is subsampling the image before creating the texture, probably because
>VTK thinks it is too large for your graphics card.
>
>Try using
>atext DebugOn
>
>and see what kind of info it gives you.  You might have to break the
>image into patches in order to render it at full resolution.
>
>  - David
>
>
>On Mon, 30 Aug 2004, Patrick Lowry wrote:
>
> > David:
> >
> > The TIFF is 8-Bit Paletted.  A comparitive image is shown below.  The TIFF
> > being loaded is on the left and a capture of the rendered texture map is on
> > the right.  The script has the 32-bit flag setting you suggested.   It is a
> > satellite image showing roads etc.
> >
> > Thanks for your help.
> >
> > Cheers,
> > Patrick Lowry
> >
> > Comp.jpg
> >
> >
> > At 01:17 PM 8/30/2004, you wrote:
> > >Hi Patrick,
> > >
> > >What do you mean by "image characteristics"?  I'm guessing that your
> > >image is either 8-bit greyscale or 24-bit RGB if it is a TIFF.  If
> > >this is the case, then VTK will use the data as a texture without
> > >any conversion, and the only things that should impact quality are
> > >the 32-bit flag I mentioned, and the actor's lighting properties.
> > >
> > >By "low quality" do you mean the image looks noisy, or do you mean
> > >that the contrast is poor?
> > >
> > >On Mon, 30 Aug 2004, Patrick Lowry wrote:
> > >
> > > > Hi David:
> > > >
> > > > Thanks for the quick reply.
> > > >
> > > > I tried your recommended setting and it didn't change the quality.
> > > >
> > > > Do image characteristics affect how they render?
> > > >
> > > > Patrick
> > > >
> > > > At 08:36 AM 8/30/2004, you wrote:
> > > > >Hi Patrick,
> > > > >
> > > > >Some graphics cards default to 16-bit textures, be sure to force
> > > > >VTK to use 32-bit textures:
> > > > >
> > > > >atext SetQualityTo32Bit
> > > > >
> > > > >  - David
> > > > >
> > > > >
> > > > >On Mon, 30 Aug 2004, Patrick Lowry wrote:
> > > > >
> > > > > > To All:
> > > > > >
> > > > > > The texture mapping capabilities of VTK are amazing but I 
> noticed image
> > > > > > quality loss from the original TIFF.  Texture mapping done by a
> > > commercial
> > > > > > program I have does not suffer the same quality loss.  The essence
> > > of the
> > > > > > image part of the TCL script are shown below.  Any ideas on 
> preventing
> > > > > > image quality loss?
> > > > > >
> > > > > > Thanks in advance.
> > > > > >
> > > > > > Patrick Lowry
> > > > > >
> > > > > > .
> > > > > > .
> > > > > > .
> > > > > > vtkTIFFReader readTIFF
> > > > > >    readTIFF SetFileName "data/test1comp.TIF"
> > > > > >    readTIFF Update
> > > > > > vtkTexture atext
> > > > > >    atext SetInput [readTIFF GetOutput]
> > > > > >    atext InterpolateOn
> > > > > > .
> > > > > > .
> > > > > > .
> > > > > > vtkTextureMapToPlane test
> > > > > >    test SetInput [normals GetOutput]
> > > > > >    test SetOrigin $xmin $ymin 0.0
> > > > > >    test SetPoint1 $xmax $ymin 0.0
> > > > > >    test SetPoint2 $xmin $ymax 0.0
> > > > > >
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