After vtk.js' ImageCPRMapper class example is run, how do I get the image coordinates of the center line on the cpr plane in stretch and straighten mode

[flourishing (flourish)]

Thank you very much for your careful answer. By the way, in the process of debugging, I found that when the center line is rotated, the x coordinate of the first point has been changing, not rotating around itself, but the x value of the first coordinate of the reference center line remains unchanged no matter how it is rotated