For vtk 9.0.1, has vtkImageReslice use the direction of image?

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I am using vtkImageReslice in my project, and I find a stranger thing.

The direction of vtkImageData is not a identify matrix, thus I adjust the direction by:

    x = [0, 1, 0]
    y = [1, 0, 0]
    z = [0, 0, 1]
    image.SetDirectionMatrix(x[0], y[0], z[0], x[1], y[1], z[1], x[2], y[2], z[2])

Then, the vtkImageReslice code is:

directionMatrix = image.GetDirectionMatrix()
center = image.GetCenter()
dirElement = [0]*9
directionMatrix.DeepCopy(dirElement, directionMatrix)

x = [dirElement[0], dirElement[3], dirElement[6]]
y = [dirElement[1], dirElement[4], dirElement[7]]
z = [dirElement[2], dirElement[5], dirElement[8]]

a = [x[0],x[1],x[2]]
b = [y[0],y[1],y[2]]
c = [z[0],z[1],z[2]]
axialElement = [
    a[0], b[0], c[0], center[0],
    a[1], b[1], c[1], center[1],
    a[2], b[2], c[2], center[2],
    0,    0,    0,    1
]

reslice = vtk.vtkImageReslice()
reslice.SetInputData(image)
reslice.SetAutoCropOutput(True)
reslice.SetOutputDimensionality(2)
reslice.SetInterpolationModeToCubic()
reslice.SetSlabNumberOfSlices(1)
reslice.SetOutputSpacing(0.35, 0.35, 0.35)

resliceAxes = vtk.vtkMatrix4x4()
resliceAxes.DeepCopy(axialElement)
reslice.SetResliceAxes(resliceAxes)
reslice.Update()

In the above code, I use the center and direction of vtkImageData to reslice the image, and the result is fine.

However, if I adjust the vtkImageData as following:

    x = [0, 1, 0]
    y = [1, 0, 0]
    z = [0, 0, -1] ########### the original is [0, 0, 1]
    image.SetDirectionMatrix(x[0], y[0], z[0], x[1], y[1], z[1], x[2], y[2], z[2])

Then, the resliced image is all zero.

Then, I have a look into the source code of vtkImageReslice, in the RequestInformation, there is a piece of code:

// line 992
  double inCenter[3];
  for (i = 0; i < 3; i++)
  {
    inCenter[i] = inOrigin[i] + 0.5 * (inWholeExt[2 * i] + inWholeExt[2 * i + 1]) * inSpacing[i];
  }

When calculate the inCenter, it do not conside the direction of vtkImageData, thus the image.GetCenter() may be outside of vtkImageReslice.outWholeExt. And I think the may be the reason why z=[0, 0, -1] make the output of vtkImageReslice zeros.

I don’t know whether my guess is correct. Does anyone know whether the vtkImageReslice take the direction of vtkImageData into consider?

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