[Insight-users] ITK Vector Field to VTK

[Karthik Krishnan]

Reinhard Hameeteman wrote:

>The VTK Image Data is below.
>I'm not really sure if this is seen as a vector image:
>Point Data
> Scalars
> Number Of Components: 3
>but
>Vectors: (none)
>
>  
>
NumberOfScalarComponents: 3

is what you want, which is true in the PrintSelf below. 
ImageToVTKImageFilter can handle vector images. The glyphs pointing in 
the same direction is because of something else.   Just to be sure, I 
did write out some dummy code to make sure...

#include "itkImage.h"
#include "itkImageToVTKImageFilter.h"
#include "vtkMetaImageWriter.h"

int main( int argc, char * argv[] )
{
  typedef    itk::Vector< float, 3 >    InputPixelType;
  static const int ImageDimension=3;
  typedef itk::Image< InputPixelType,  ImageDimension >   ImageType;
  ImageType::Pointer image = ImageType::New();     
  ImageType::IndexType start;
  start[0] =   0;  // first index on X
  start[1] =   0;  // first index on Y
  start[2] =   0;  // first index on Z
  ImageType::SizeType  size;
  size[0]  = 20;  // size along X
  size[1]  = 20;  // size along Y
  size[2]  = 20;  // size along Z
  ImageType::RegionType region;
  region.SetSize( size );
  region.SetIndex( start );
  image->SetRegions( region );
  image->Allocate();
  InputPixelType g( 0.0 );
  image->FillBuffer( g );
  ImageType::IndexType idx;
  idx[0]=10;idx[1]=10;idx[2]=10;
  InputPixelType p( 255. );
  image->SetPixel( idx, p );
  typedef itk::ImageToVTKImageFilter< ImageType > FilterType;
  FilterType::Pointer f = FilterType::New();
  f->SetInput( image );
  vtkMetaImageWriter * writer1 = vtkMetaImageWriter::New();
  writer1->SetInput( f->GetOutput() );
  writer1->SetFileName( "foo.mhd" );
  writer1->SetFileDimensionality( 3 );
  writer1->Update();
  re

>Because the class description of VTKImageExport states that
>"Currently VTKImageExport does not support pixel types with multiple
>components"  I figured this caused the single component in my vtk
>image: all glyph vectors pointing in the same direction.
>
>I tried to visualise the field as follows (with the type defenitions
>included for your information):
>
>typedef itk::Vector<float, 3>           VectorType;
>typedef itk::Image<VectorType, 3> DeformationFieldType;
>typedef itk::ImageToVTKImageFilter
>               <DeformationFieldType > ITK2VTKAdaptorFilterType;
>
>  m_DeformationField = DeformationFieldType::New();
>// Calculation of the field
>  
>  m_ITK2VTKAdaptor  = ITK2VTKAdaptorFilterType::New();
>  m_ITKVTKAdaptor->SetInput( m_DeformationField  );
>
>  m_ExtractVOI  = vtkExtractVOI::New();
>  m_ExtractVOI->SetInput( m_ITK2VTKAdaptor->GetOutput() );
>  m_ExtractVOI->SetVOI( -1000, 1000, -1000, 1000, 30,30 );
>  m_ExtractVOI->SetSampleRate( 4,4,4 );
>
>  vtkArrowSource* vector = vtkArrowSource::New();
>  m_VectorGlyph->SetInput( m_ExtractVOI->GetOutput() );
>  m_VectorGlyph->SetSource( vector->GetOutput() );
>  m_VectorMapper->SetInput( m_VectorGlyph->GetOutput() );
>  m_VectorActor->SetMapper( m_VectorMapper );
>
>
>vtkImageData (031F5EC0)
>  Debug: Off
>  Modified Time: 5528
>  Reference Count: 1
>  Registered Events: (none)
>  Source: 031F5DA8
>  Release Data: Off
>  Data Released: False
>  Global Release Data: Off
>  MaximumNumberOfPieces: -1
>  PipelineMTime: 5520
>  UpdateTime: 5529
>  UpdateExtent: Not Initialized
>  Update Number Of Pieces: 1
>  Update Piece: 0
>  Update Ghost Level: 0
>  RequestExactExtent: Off
>   UpdateExtent: 0, 49, 0, 49, 0, 49
>  WholeExtent: 0, 49, 0, 49, 0, 49
>  Field Data:
>    Debug: Off
>    Modified Time: 5515
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 0
>    Number Of Components: 0
>    Number Of Tuples: 0
>  Locality: 0
>  NumberOfConsumers: 0
>  ExtentTranslator: (031D32F0)
>  MaximumNumberOfPieces: -1
>  Number Of Points: 125000
>  Number Of Cells: 117649
>  Cell Data:
>    Debug: Off
>    Modified Time: 5517
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 0
>    Number Of Components: 0
>    Number Of Tuples: 0
>    Copy Flags: ( 1 1 1 1 1 )
>    Scalars: (none)
>    Vectors: (none)
>    Normals: (none)
>    TCoords: (none)
>    Tensors: (none)
>  Point Data:
>    Debug: Off
>    Modified Time: 5527
>    Reference Count: 1
>    Registered Events: (none)
>    Number Of Arrays: 1
>    Array 0 name = NULL
>    Number Of Components: 3
>    Number Of Tuples: 125000
>    Copy Flags: ( 1 1 1 1 1 )
>    Scalars:
>      Debug: Off
>      Modified Time: 5524
>      Reference Count: 1
>      Registered Events: (none)
>      Name: (none)
>      Number Of Components: 3
>      Number Of Tuples: 125000
>      Size: 375000
>      MaxId: 374999
>      LookupTable: (none)
>      Array: 0A800044
>    Vectors: (none)
>    Normals: (none)
>    TCoords: (none)
>    Tensors: (none)
>  Bounds:
>    Xmin,Xmax: (-140.532, -104.165)
>    Ymin,Ymax: (-47.5429, -11.1757)
>    Zmin,Zmax: (11.537, 158.537)
>  Compute Time: 0
>  Release Data: Off
>  ScalarType: 10
>  NumberOfScalarComponents: 3
>  Spacing: (0.742188, 0.742188, 3)
>  Origin: (-140.532, -47.5429, 11.537)
>  Dimensions: (50, 50, 50)
>  Increments: (3, 150, 7500)
>  Extent: (0, 49, 0, 49, 0, 49)
>  WholeExtent: (0, 49, 0, 49, 0, 49)
>
>2005/8/15, Karthik Krishnan <Karthik.Krishnan at kitware.com>:
>  
>
>>Reinhard Hameeteman wrote:
>>
>>    
>>
>>>Hi,
>>>
>>>Is it possible to export a vector image defined as:
>>>
>>>typedef itk::Vector<float, 3>           VectorType;
>>>typedef itk::Image<VectorType, 3> DeformationFieldType;
>>>
>>>to VTK?
>>>
>>>I can save the vector field and read it in paraview, but I want the
>>>visualisation in my own application and using itkImageToVTKImageFilter
>>>I only get a scalar (x-component?) in the vtk image.
>>>
>>>
>>>
>>>      
>>>
>>I've exported data from ITK to VTK with image pixel types of Vector<
>>double, 3 >, using the ImageToVTKImageFilter before and I am quite
>>certain it works.
>>
>>Incidentally, there was a bug in the itkVTKImageIO.cxx that caused bogus
>>to be written out when writing multi-component images, but that would
>>only affect you if you were writing out VTK images from ITK and reading
>>them with VTK or vice versa.
>>
>>Can you print out the vtkImageData that you get after exporting to VTK ?
>>
>>    
>>
>>>Reinhard
>>>_______________________________________________
>>>Insight-users mailing list
>>>Insight-users at itk.org
>>>http://www.itk.org/mailman/listinfo/insight-users
>>>
>>>
>>>
>>>      
>>>
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>