# Mapping electromagnetic tracking error

**URL:** <https://discourse.slicer.org/t/mapping-electromagnetic-tracking-error/16717>\
**Category:** Support\
**Created:** [March 23, 2021, 12:04pm UTC](https://discourse.slicer.org/t/mapping-electromagnetic-tracking-error/16717 "2021-03-23T12:04:42Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![marco.cavaliere](https://avatars.discourse-cdn.com/v4/letter/m/e0b2c6/32.png) [@marco.cavaliere](https://discourse.slicer.org/u/marco.cavaliere)\
**Post date:** [March 23, 2021, 12:04pm UTC](https://discourse.slicer.org/t/mapping-electromagnetic-tracking-error/16717/1 "2021-03-23T12:04:42Z")

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Hi,

I’m trying to visualize the position error between 2 tracking systems (electromagnetic and optical) in Slicer, as it is done in this paper [https://doi.org/10.1117/12.2082330](https://doi.org/10.1117/12.2082330)

I’m following this tutorial  
[SlicerIGT-U19\_EmFieldDistorition.pptx - Microsoft PowerPoint Online (live.com)](https://onedrive.live.com/view.aspx?cid=7230d4dec6058018&page=view&resid=7230D4DEC6058018!5624&parId=7230D4DEC6058018!2937&authkey=!AGQkSCZOwjVYXw8&app=PowerPoint)

but the module required is not loaded correctly.

Thank you,  
Marco

Operating system: Windows 10  
Slicer version: 4.11  
Expected behavior: Position Error Tracking module  
Actual behavior: module failed to load

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**Author:** ![lassoan](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/lassoan/32/13_2.png) [@lassoan](https://discourse.slicer.org/u/lassoan)\
**Post date:** [March 24, 2021, 5:21pm UTC](https://discourse.slicer.org/t/mapping-electromagnetic-tracking-error/16717/2 "2021-03-24T17:21:39Z")

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We have not tested this module with latest Slicer versions, but if there are failures then it is most likely due to slight Python2/3 syntax and Slicer API changes, which should be easy to address. Have a look at the Python console (Ctrl-3) for errors and try to fix them. If you get stuck with any specific errors then let us know.