Extract the annotated plane in 3D image

I am doing a view plane localization research. First I need to annotate the plane as the ground-truth. I use the “Markups” module of 3D Slicer to annotate the plane. But after i annotated the plane and export the json file. I used the “baseToNode” as the rotation matrix to extract the annotated plane, but i can not get the annotated plane. How can i get the annotated plane using python? Should I using the key “center” and “normal” in the json file?

This is my annotate plane!

Yes, you can use center and normal properties in the json file. If you want to create a markup plane JSON file then you can follow this example in the script repository.