[vtkusers] How read the scalar data in a vtkvolume16reader object? (the scalar data associated with some specified voxel)

[Amy Henderson]

The problem is that the data isn't actually read from your file until 
Update is called on the reader.  Try adding the line v16->Update(); before 
you try to get its output.

- Amy

At 06:41 AM 4/30/2004, Dumont Nicolas wrote:
>Hello !!! I am using vtkvolume16reader to read the CT data quarter.1-93
>I wish to modify the scalar data at some voxel. So first I try to copy
>volume16reader->GetOutput() (which is a vtkImageData object ?) in a new
>vtkImageData object.
>
>Here is the c++ code i tried:
>
>vtkVolume16Reader *v16 = vtkVolume16Reader::New();
>     v16->SetDataDimensions(64,64);
>     v16->SetDataByteOrderToLittleEndian();
>     v16->SetFilePrefix (argv[1]);
>     v16->SetImageRange(1, 93);
>     v16->SetDataSpacing (3.2, 3.2, 1.5);
>
>vtkImageData *imageData = vtkImageData::New();
>         imageData->SetDimensions(64,64,93);
>         imageData->SetSpacing(3.2,3.2,1.5);
>         imageData->SetOrigin(0.0,0.0,0.0);
>         imageData->SetScalarTypeToUnsignedChar();
>         imageData->SetNumberOfScalarComponents(1);
>         imageData->AllocateScalars();
>         imageData->GetPointData()->CopyAllOn();
>         imageData->GetPointData()->CopyScalarsOn();
>
>for (int i=0; i<64*64*93; i++)
>{
>     imageData->GetPointData()->CopyData( v16->GetOutput()->GetPointData(),
>i, i );
>}  //this give me a all black volume, only the outline of the data is visible
>
>
>/* unsigned char *ptr2 =(unsigned char *)
>v16->GetOutput()->GetScalarPointer();
>unsigned char *ptr =(unsigned char *) imageData->GetScalarPointer();
>
>for (int i=0; i<64*64*93; i++)
>{
>         *ptr = *ptr2;
>         ptr++;
>         ptr2++;
>}*/
>// this returns the error that ptr2 points to memory adress 0x00000000 and
>cant be read.
>
>so .... How can I read the scalar data at some specified voxel in a
>vtkvolume16reader object?
>thanks in advance,
>Nicolas D.
>Belgium, ulg.
>
>Here my hole code :
>
>#include <iostream>
>#include <vector>
>#include <string>
>#include <stdio.h>
>
>#include "vtkRenderer.h"
>#include "vtkRenderWindow.h"
>#include "vtkRenderWindowInteractor.h"
>#include "vtkVolume16Reader.h"
>#include "vtkVolumeRayCastCompositeFunction.h"
>#include "vtkVolumeRayCastMapper.h"
>#include "vtkVolumeRayCastCompositeFunction.h"
>#include "vtkPiecewiseFunction.h"
>#include "vtkColorTransferFunction.h"
>#include "vtkVolumeProperty.h"
>#include "vtkVolume.h"
>#include "vtkOutlineFilter.h"
>#include "vtkPolyDataMapper.h"
>#include "vtkActor.h"
>#include "vtkCamera.h"
>#include "vtkProperty.h"
>#include "vtkInteractorStyleTrackballCamera.h"
>#include "vtkImageData.h"
>#include "vtkPointData.h"
>#include "vtkCellData.h"
>#include "vtkDataSetAttributes.h"
>
>
>
>
>
>int main (int argc, char **argv)
>{
>   if (argc < 2)
>     {
>       cout << "Usage: " << argv[0] << " DATADIR/headsq/quarter " << endl;
>     return 1;
>     }
>
>
>vtkVolume16Reader *v16 = vtkVolume16Reader::New();
>     v16->SetDataDimensions(64,64);
>     v16->SetDataByteOrderToLittleEndian();
>     v16->SetFilePrefix (argv[1]);
>     v16->SetImageRange(1, 93);
>     v16->SetDataSpacing (3.2, 3.2, 1.5);
>
>
>
>vtkImageData *imageData = vtkImageData::New();
>         imageData->SetDimensions(64,64,93);
>         imageData->SetSpacing(3.2,3.2,1.5);
>         imageData->SetOrigin(0.0,0.0,0.0);
>         imageData->SetScalarTypeToUnsignedChar();
>         imageData->SetNumberOfScalarComponents(1);
>         imageData->AllocateScalars();
>         imageData->GetPointData()->CopyAllOn();
>         imageData->GetPointData()->CopyScalarsOn();
>
>/*for (int i=0; i<64*64*93; i++)
>{
>         imageData->GetPointData()->CopyData( 
> v16->GetOutput()->GetPointData(), i,
>i );
>}*/
>
>unsigned char *ptr2 =(unsigned char *) v16->GetOutput()->GetScalarPointer();
>unsigned char *ptr =(unsigned char *) imageData->GetScalarPointer();
>
>for (int i=0; i<64*64*93; i++)
>{
>         *ptr = *ptr2;
>         ptr++;
>         ptr2++;
>}
>
>vtkVolumeRayCastCompositeFunction  *compositeFunction =
>vtkVolumeRayCastCompositeFunction::New();
>
>
>vtkVolumeRayCastMapper *volumeMapper = vtkVolumeRayCastMapper::New();
>     volumeMapper->SetInput(imageData);
>     volumeMapper->SetVolumeRayCastFunction(compositeFunction);
>         //volumeMapper->CroppingOn();
>         //volumeMapper->SetCroppingRegionPlanes(60,100,60,100,60,100);
>         //volumeMapper->SetCroppingRegionFlags(0x7ffffdf);
>
>
>vtkPiecewiseFunction *tfun = vtkPiecewiseFunction::New();
>     tfun->AddPoint(399.0,0.0);
>     tfun->AddPoint(400.0,0.2);
>     tfun->AddPoint(700.0,0.2);
>     tfun->AddPoint(701.0,0.05);
>     tfun->AddPoint(1199,0.05);
>     tfun->AddPoint(1200,0.2);
>     tfun->AddPoint(2649,0.2);
>     tfun->AddPoint(2650,0.2);
>
>vtkColorTransferFunction *ctfun = vtkColorTransferFunction::New();
>     ctfun->AddRGBPoint(350,  1.0,  1.0,  1.0);
>     ctfun->AddRGBPoint(500,  1.0,  0.5,  0.5);
>     ctfun->AddRGBPoint(650,  1.0,  0.5,  0.5);
>     ctfun->AddRGBPoint(800,  0.6,  0.5,  0.3);
>     ctfun->AddRGBPoint(1000, 0.6,  0.5,  0.3);
>     ctfun->AddRGBPoint(1500, 1.0,  1.0,  1.0);
>     ctfun->AddRGBPoint(2000, 1.0,  0.1,  0.1);
>     ctfun->AddRGBPoint(2700, 0.0,  1.0,  0.0);
>
>
>
>vtkVolumeProperty *volumeProperty = vtkVolumeProperty::New();
>     volumeProperty->SetColor(ctfun);
>     volumeProperty->SetScalarOpacity(tfun);
>     volumeProperty->SetInterpolationTypeToLinear();
>     volumeProperty->ShadeOn();
>
>
>vtkVolume *newvol = vtkVolume::New();
>     newvol->SetMapper(volumeMapper);
>     newvol->SetProperty(volumeProperty);
>
>
>
>vtkOutlineFilter *outline = vtkOutlineFilter::New();
>     outline->SetInput((vtkDataSet *) v16->GetOutput());
>
>
>vtkPolyDataMapper *outlineMapper = vtkPolyDataMapper::New();
>     outlineMapper->SetInput(outline->GetOutput());
>
>vtkActor *outlineActor = vtkActor::New();
>     outlineActor->SetMapper(outlineMapper);
>     outlineActor->GetProperty()->SetColor(1,1,1);
>
>
>
>vtkCamera *Camera = vtkCamera::New();
>     Camera->SetViewUp (0, 0, -1);
>     Camera->SetPosition (140, 600, -100);
>     Camera->SetFocalPoint (100, 100, 75);
>     Camera->ComputeViewPlaneNormal();
>
>
>vtkRenderer *ren = vtkRenderer::New();
>     ren->AddActor(outlineActor);
>     ren->AddVolume(newvol);
>     ren->SetBackground(0,0,0);
>     ren->SetActiveCamera(Camera);
>
>
>vtkRenderWindow *renWin = vtkRenderWindow::New();
>     renWin->AddRenderer(ren);
>     renWin->SetSize(640,480);
>
>
>vtkInteractorStyleTrackballCamera *style =
>vtkInteractorStyleTrackballCamera::New();
>
>vtkRenderWindowInteractor *iren = vtkRenderWindowInteractor::New();
>     iren->SetRenderWindow(renWin);
>     iren->SetInteractorStyle(style);
>     iren->Initialize();
>     iren->Start();
>
>
>
>
>     v16->Delete();
>     compositeFunction->Delete();
>     volumeMapper->Delete();
>     tfun->Delete();
>     ctfun->Delete();
>     volumeProperty->Delete();
>     newvol->Delete();
>     outline->Delete();
>     outlineMapper->Delete();
>     outlineActor->Delete();
>     Camera->Delete();
>     ren->Delete();
>     renWin->Delete();
>     iren->Delete();
>     style->Delete();
>
>   return 0;
>}
>
>
>
>
>
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