[vtkusers] vtkImageData Beginner Question

[Francois Bertel]

Hello,

I think you should use SetExtent(), not SetDimensions().

because the code of vtkImageData::SetDimensions() is actually:

  SetExtent(0, dim[0]-1, 0, dim[1]-1, 0, dim[2]-1);

Also Origin is the position in world coordinate of the point of
extent(0,0,0): the origin does not have to be part of the dataset, in
other words, the dataset extent does not have to start at (0,0,0) and
the origin can be outside of the dataset bounding box.


On Fri, Jul 3, 2009 at 5:50 PM, Michael
Jackson<mike.jackson at bluequartz.net> wrote:
> I have consulted all the vtk and paraview books but I am just coming up
> empty on this.
>
> Here is what I have: A volume of Grayscale pixels being read from a file.
> The data represents a volume starting at 46979 Microns in x and 48443
> Microns in Y. Each Slice in the z direction represents 1.2 microns. The
> "scaling" is 0.207987 Microns/Pixel. The volume is roughly 821 slices by
> about 1500 Microns in X and about 1500 Microns in Y.
>
>  Here is what I would like: This to show in a window (ParaView) so that when
> I set the "Show Axis" all the values are "correct", ie, the values should
> start at about 46979,48443,0 and go to their maximum values. Currently I
> have the user fill in some text fields that represent the VOI that the user
> would like to render. When the code hits what I have written I either get a
> crash or errors of the type:
>
> ERROR: In
> /Users/Shared/Kitware-CVS/ParaView3/VTK/Filtering/vtkImageData.cxx, line
> 2101
> vtkImageData (0x122a31b70): GetPointer: Pixel (46979, 48443, 0) not in
> current extent: (0, 7432, 0, 7393, 0, 1)
>
> or
>
> Warning: In
> /Users/Shared/Kitware-CVS/ParaView3/VTK/Filtering/vtkDataSet.cxx, line 414
> vtkImageData (0x12a0e5ee0): Point array RoboMet Voxels with 1 components,
> has 0 tuples but there are only -1048158596 points
>
>
> Here is the code that I am using to init the vtkImageData object during the
> pipeline excution:
>
> int dims[3];
> dims[0] = (requestedExtent[1] -
> requestedExtent[0])/this->CurrentScalingFactor;
> dims[1] = (requestedExtent[3] -
> requestedExtent[2])/this->CurrentScalingFactor;
> dims[2] =  requestedExtent[5] - requestedExtent[4] + 1;
> if (dims[2] == 0)
> {
> dims[2] = 1;
> }
> output->SetDimensions(dims[0], dims[1], dims[2]);
> output->SetSpacing(this->DataSpacing);
> output->SetOrigin(this->DataOrigin);
> output->SetScalarType(VTK_TYPE_UINT8);
>
> //output->SetExtent(requestedExtent);
> output->SetNumberOfScalarComponents( 1 );
> output->AllocateScalars();
> output->GetPointData()->GetScalars()->SetName("RoboMet Voxels");
> output->GetPointData()->SetActiveScalars("RoboMet Voxels");
>
> Here is the values of the requestedExtent when the method gets called:
>
> 46979 48525 48443 49981 0 0
>
> Any help is appreciated..
> _________________________________________________________
> Mike Jackson                  mike.jackson at bluequartz.net
> BlueQuartz Software                    www.bluequartz.net
> Principal Software Engineer                  Dayton, Ohio
>
>
>
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-- 
François Bertel, PhD  | Kitware Inc. Suite 204
1 (518) 371 3971 x113 | 28 Corporate Drive
                      | Clifton Park NY 12065, USA