# Unable to factor lineal system

**URL:** <https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607>\
**Category:** VMTK\
**Created:** [October 9, 2024, 12:09pm UTC](https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607 "2024-10-09T12:09:00Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Sofia\_Gonzalez](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sofia_gonzalez/32/78172_2.png) [@Sofia\_Gonzalez](https://discourse.slicer.org/u/Sofia_Gonzalez)\
**Post date:** [October 9, 2024, 12:09pm UTC](https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607/1 "2024-10-09T12:09:00Z")

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Hello everyone, I’m trying to compute the centerline of a carotid and it’s a .stil file.  
Someone knows why is saying that error?  
Is because of the mesh?

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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:** [October 10, 2024, 4:40am UTC](https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607/2 "2024-10-10T04:40:00Z")

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Yes, it is because of the mesh has invalid (or at least unexpected) geometry.

For example, it may be that your mesh contain the vessel wall only (thin shell) instead of the blood pool (solid). Can you post a screenshot?

You can fix up the mesh by loading it as Segmentation and then editing it in Segment Editor module.

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<div class="post-metadata">

**Author:** ![Sofia\_Gonzalez](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sofia_gonzalez/32/78172_2.png) [@Sofia\_Gonzalez](https://discourse.slicer.org/u/Sofia_Gonzalez)\
**Post date:** [October 10, 2024, 7:37am UTC](https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607/3 "2024-10-10T07:37:12Z")

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Yes that’s true!! I only have my .stl the surface of my carotid. But I also have the x,y,z of the mesh and u,v,w. And I have to merge it in a one file right? Do you know how to merge the coordinates of the mesh and velocity with the surface?

thanksss

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<div class="post-metadata">

**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:** [October 15, 2024, 11:36pm UTC](https://discourse.slicer.org/t/unable-to-factor-lineal-system/39607/4 "2024-10-15T23:36:10Z")

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I don’t know what u, v, w stores - texture coordinates, velocity vector components, …? Anyway, you cannot store any of these in a standard STL file. You can store point and cell scalars in VTK mesh file formats and Slicer can read and visualize them.