[vtkusers] How to get voxel value from vtkImageData using C++?

[Yi-Yu Chou]

Hi,

I built a vtk class, and I passed a vtkImageData from python to it. In this 
function I want to read the intensity of one voxel, and the function is 
like :

void vtkLocalExample::SetOriImg(vtkImageData *img)
{
  vtkPointData* pData = (vtkPointData*) img->GetPointData();
  vtkDataArray* imgArray = (vtkDataArray*) pData->GetScalars();
  float vox_val = imgArray->GetComponent(2000000,0);   
  printf("voxel value = %f \n", vox_val);
}

However, I got nothing from the output :
voxel value = nan
ps. the image size is 256x256x124
What's wrong with my code ?
Any suggestion would be appreciated !!!

YY

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