[vtkusers] Please help

[AHMED MAHMOUD]

Hello ,
I have 16 bit image I used this pipeline to access the pixels values
vtkVolume16Reader reader
vtkStructuredPoints sp
sp=reader->GetImage (1)
vtkScalars scalar
scalar = sp->GetPointData()->GetScalars()
and it works,
but when I used the same pipeline to read bmp data the scalar  pointer was
Null why ?? here is my code
///////////////////
vtkBMPReader reader
vtkImageToStructuredPoints  toStructuredPoints
toStructuredPoints->SetInput(reader->GetOutput())
vtkStructuredPoints sp
sp=toStructuredPoints->GetOutput()
vtkScalars scalar
scalar = sp->GetPointData()->GetScalars();
////////////
Why scalar is Null ??
Thank you very much