[vtkusers] Re: Texture mapping on a 3D surface.

[Goodwin Lawlor]

Hi Jens,

Just try fTextureData as the source to probe...

 vtkProbeFilter* probe = vtkProbeFilter::New();
    probe->SetInput(fPolyData);   // My instance of vtkPolyData
    probe->SetSource(fTextureData);

probe will interpolate the values at the input points.


hth

Goodwin


----- Original Message ----- 
From: "Jens Ivar Jørdre" <jensivar at fmri.no>
To: "Goodwin Lawlor" <goodwin.lawlor at ucd.ie>; <vtkusers at public.kitware.com>
Sent: Wednesday, June 08, 2005 3:25 PM
Subject: Re: [vtkusers] Re: Texture mapping on a 3D surface.


> Hi Goodwin.
>
> I think this is the way to go, although I have some difficulty getting
> the coloring right. The problem I face comes about when I want to
> prepare the MR image volume as the source for vtkProbeFilter.
>
> When I fill an instance of vtkImageData (called fTextureData) with MR
> voxel values I guess I should this info as cell attributes, right? I
> mean the voxel data corresponds to attributes of cells in vtkImage.
> Hence I fill an instance of vtkFloatArray (called textureArray) with
> voxel values and call
> fTextureData->GetCellData()->SetScalars(textureArray);
>
> However, the entities whose color I want to determine are points.
> Therfoe I try to use vtkCellDataToPointData in order to determine the
> point attributes in fTextureData. The output from this filter I then
> pipe into vtkProbeFilter. This part of the pipe line looks like this:
>
> vtkCellDataToPointData* ctp = vtkCellDataToPointData::New();
>    ctp->SetInput(fTextureData);
>    ctp->PassCellDataOn();
>
> vtkProbeFilter* probe = vtkProbeFilter::New();
>    probe->SetInput(fPolyData);   // My instance of vtkPolyData
>    probe->SetSource(ctp->GetPolyDataOutput());
>
> The result of this is that probe complains about the source being empty.
>   Does anyone see what I'm doing wrong? It kind of looks as if I don't
> use the vtkCellDataToPointData filter properly.
>
> Kind regards
> Jens Ivar Jørdre
>
> Goodwin Lawlor skrev:
> > Hi Jens,
> >
> > Use vtkProbeFilter with your (vtkPolyData) tessellated surface as the
input
> > and your (vtkImageData) MR image volume as the source. The output will
be
> > the same vtkPolyData as the input with some point scalar values sampled
from
> > the source.
> >
> > hth,
> >
> > Goodwin
> >
> >
> > "Jens Ivar Jørdre" <jensivar at fmri.no> wrote in message
> > news:42A6ADF7.60600 at fmri.no...
> > Howdy.
> >
> > Here comes a question from someone who quite recently started using VTK
> > 4.2 on Windows XP. So far I've used VTK to visualize a tessellated
> > surface of the brain  reconstructed from MR images.
> >
> > I then want to move on to color the surface in grey tones according to
> > voxel intensities of the surface points. I first tried to use vtkTexture
> > to load a (3D) vtkImageData filled with voxel intensities from the MR
> > image volume. However, since vtkTexture only supports 2D texture maps I
> > had to give up this effort.
> >
> > Then I've tried to assign texture coordinates to the points that define
> > the tessellated surface, but I see no effect on the surface rendered.
> > Does anyone have some example for me to look at? I don't find relevant
> > suggestions in the examples shipped with VTK.
> >
> > Kind regards
> > Jens Ivar Jørdre
> >
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