I would like to know how to get coordinates for the boundaries of a markup plane in IJK.
In fiducial point case, my understanding is that we can get the following codes:
world = [0, 0, 0, 0]
fiducialNode.GetNthFiducialWorldCoordinates(index, world)
then something like this
p_Ras = [coord[0], coord[1], coord[2], 1.0]
p_Ijk = RasToIjkMatrix.MultiplyDoublePoint(p_Ras)

but I am wondering how to get the coordinates of plane nodes. I couldn’t find the function for it in the vtkMRMLMarkupsPlaneNode class.

Markups plane coordinate system is described in the documentation: “Origin of plane at 0,0,0, XYZ axis aligned to XYZ unit vectors”. For example, homogeneous coordinate of one of the corners is [planeBounds[0], planeBounds[2], 0, 1].