Python, C++ VTK Affine transformation

Question

My first question here. I am working to a visualization pipeline with the vtk library (neuroimaging data). However, I am really struggling with the affine handling. From the documentation (example, doxygen, books) It seems I should use something like this:

transform = vtkTransform()
matrix_vtk =vtkMatrix4x4()
matrix_vtk.DeepCopy((1, 0, 0, 0, 0, 1, 0, 1, 0,0,1,0,0,0,0,1))
transform.SetMatrix(matrix_vtk)
transform_filter = vtkTransformPolyDataFilter()
transform_filter.SetTransform(transform)
dataset_mapper = vtk.vtkDataSetMapper()
dataset_mapper.SetInputConnection(transform_filter.GetOutputPort())
actor.SetMapper(dataset_mapper)

However the results are not those I expected :D The complete code is:

from vtk import *

fname_trk = "test/L113619_imfs_d10_110mm.trk"
fname_vtk = "test/L113619_imfs_d10.vtk"
fname_ply = "test/113619_Lwhite.ply"

reader = vtkPLYReader()
reader.SetFileName(fname_ply)
reader_vtk = vtkPolyDataReader()
reader_vtk.SetFileName(fname_vtk)

ren = vtkRenderer()
wren = vtkRenderWindow()
iren = vtkRenderWindowInteractor()
wren.AddRenderer(ren)
iren.SetRenderWindow(wren)
mapper = vtkPolyDataMapper()
mapper.SetInputConnection(reader.GetOutputPort())
mapper_vtk = vtkPolyDataMapper()
mapper_vtk.SetInputConnection(reader_vtk.GetOutputPort())
actor = vtkActor()
actor.SetMapper(mapper)
actor_vtk = vtkActor()
# actor_vtk.SetMapper(mapper_vtk)
ren.AddActor(actor_vtk)
ren.AddActor(actor)

transform = vtkTransform()
matrix_vtk =vtkMatrix4x4()
matrix_vtk.DeepCopy((1, 0, 0, 0, 0, 1, 0, 1, 0,0,1,0,0,0,0,1))
transform.SetMatrix(matrix_vtk)
transform_filter = vtkTransformPolyDataFilter()
transform_filter.SetTransform(transform)
dataset_mapper = vtk.vtkDataSetMapper()
dataset_mapper.SetInputConnection(transform_filter.GetOutputPort())
actor.SetMapper(dataset_mapper)
actor.SetMapper(datasetmapper)

iren.Initialize()
iren.Start()

Any suggestions?

Answer 1

You didn't connect any input to filter, something like transform_filter.SetInputData(reader.GetOutputPort()) .

It would be helpful if you could write what you expect.

Answer 2

your process is right, however, your output is not correctly defined. you can run it line by line and follow your output.