Save transformation matrix programmatically after landmark registration

Development
1

Operating system: Win10
Slicer version:4.10.2
Expected behavior:
Actual behavior:

Hi guys,
I am new to slicer programming. I am loading two volume data( fixed and moving one). Then using slicer’s landmark registration module and selecting some landmark.
After registration is done I want to save the transformation matrix programmatically. If possible getting the transformation matrix after every landmark is selected.
can you please provide an example to do that?

Thanks

2

You can save node to file using slicer.util.saveNode() method. Slicer saves transforms in ITK transform file format (binary .h5 file or text .txt file).

3

I used it like below lines:
>>> slicer.util.saveNode(transformNode,“C:\Users\Johar\Desktop\CheckIT\transmat.txt”)
> False
And as you can see, I get nothing. Can you correct me and show, how to get the transform node correctly and then save?

4

Use forward slashes not backslashes :wink:

5

You can also use raw strings (add an r character before the string literal), to prevent interpreting backslash as an escape character:

slicer.util.saveNode(transformNode,r"C:\Users\Johar\Desktop\CheckIT\transmat.txt")

6

Hi @lassoan and @pieper
I tried both of your ideas. But I think I am not catching the transform node correctly.

>>> slicer.util.saveNode("Transform",r"C:/Users/transmat.txt")
Traceback (most recent call last):
  File "<console>", line 1, in <module>
  File "C:\Slicer 4.10.2\bin\Python\slicer\util.py", line 512, in saveNode
    properties["nodeID"] = node.GetID();
AttributeError: 'str' object has no attribute 'GetID'

This is how transform matrix looks like after landmark registration:

Unbenannt
Unbenannt607×630 20.6 KB

7

“Transform” is the node’s name. You can use slicer.util.getNode() method to get the node object from its name:

slicer.util.saveNode(slicer.util.getNode("Transform"),r"C:/Users/transmat.txt")

Please complete one of the Slicer programming tutorials. All these basic concepts are described there.