[vtkusers] Problem with vtkLandmarkTransform

Tue Apr 13 21:37:44 EDT 2004

Hello everyone,

I want to use vtkLandmarkTransform to do some linear transformation. I have two sets of landmarks in two different coordinate systems and want to establish the transformation between these two spaces. Basically I gave two sets of landmarks to SetSourceLandmarks and SetTargetLandmarks, and each set has the same number of points. The problem is that I couldn’t get a correct transform matrix. 

            SourceLandmarks = []

            SourceLandmarks = vtkPoints()

            SourceLandmarks.InsertNextPoint(SLandmark1)

            SourceLandmarks.InsertNextPoint(SLandmark2)

            SourceLandmarks.InsertNextPoint(SLandmark3)

            SourceLandmarks.Modified()

            TargetLandmarks = []

            TargetLandmarks = vtkPoints()

            TargetLandmarks.InsertNextPoint(TLandmark1)

            TargetLandmarks.InsertNextPoint(TLandmark2)

            TargetLandmarks.InsertNextPoint(TLandmark3)

            TargetLandmarks.Modified()

            Transform = vtkLandmarkTransform()

            Transform.SetSourceLandmarks(SourceLandmarks)

            Transfrom.SetTargetLandmarks(TargetLandmarks)

            InputX = float(entryInputLandmarkX.get())

            InputY = float(entryInputLandmarkY.get())

            InputZ = float(entryInputLandmarkZ.get())

            InputLandmark = [InputX, InputY, InputZ]

            OutputLandmark = Transform.TransformFloatPoint(InputLandmark)

When I print the outputlandmark on the screen, I just got (nan, nan, nan)

Can I get the transform matrix by GetMatrix()? Could anyone help me? If anyone has such a script, could you share it with me? 

Thank you very much!

vtk learner

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