# VMTK Module - extract center line makes the model invisible / erased!

**URL:** <https://discourse.slicer.org/t/vmtk-module-extract-center-line-makes-the-model-invisible-erased/32084>\
**Category:** Support\
**Created:** [October 7, 2023, 5:33am UTC](https://discourse.slicer.org/t/vmtk-module-extract-center-line-makes-the-model-invisible-erased/32084 "2023-10-07T05:33:14Z")\
**Posts on this page:** 1\
**Page:** 1

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**Author:** ![Henry\_Lopes](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/henry_lopes/32/67396_2.png) [@Henry\_Lopes](https://discourse.slicer.org/u/Henry_Lopes)\
**Post date:** [October 7, 2023, 5:33am UTC](https://discourse.slicer.org/t/vmtk-module-extract-center-line-makes-the-model-invisible-erased/32084/1 "2023-10-07T05:33:14Z")

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So many times (almost always) when I use the “extract center line” function of the VMTK module, the model I used as input surface is blanked (it still appears in DATA, but invisible in any view even with visibility marked on). Why is this happening?  
I am u sing the follow workaround:

1. I save the model before extracting the center line;
2. Then I extract the center line and my model is blanked (invisible);
3. I load the previously saved model and everything is ok (center line + visible module).

Am I doing something wrong, or is it a problem with my CT scan?

Thank you very much again.