# Segmentation and Volume Misaligned After Using Biomedisa

**URL:** <https://discourse.slicer.org/t/segmentation-and-volume-misaligned-after-using-biomedisa/46331>\
**Category:** Support\
**Created:** [February 27, 2026, 2:38pm UTC](https://discourse.slicer.org/t/segmentation-and-volume-misaligned-after-using-biomedisa/46331 "2026-02-27T14:38:33Z")\
**Posts on this page:** 1\
**Showing post:** 3

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**Author:** ![MrMarkus](https://avatars.discourse-cdn.com/v4/letter/m/71e660/32.png) [@MrMarkus](https://discourse.slicer.org/u/MrMarkus)\
**Post date:** [March 5, 2026, 8:09am UTC](https://discourse.slicer.org/t/segmentation-and-volume-misaligned-after-using-biomedisa/46331/3 "2026-03-05T08:09:03Z")

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Hi,

take a look at this information:

> [@Model files are now saved in LPS coordinate system](https://discourse.slicer.org/t/model-files-are-now-saved-in-lps-coordinate-system/10446):
>
> While Slicer uses RAS coordinate system internally, images, transforms, and markups files are stored in LPS coordinate system, because DICOM and all medical image computing software (maybe except a few very old ones) uses LPS coordinate system in files. However, Slicer has been still using its internal RAS coordinate system in mesh files (STL, VTK, VTP, OBJ, PLY), which [caused issues when interfacing with third-party software](https://issues.slicer.org/view.php?id=4445). Starting from tomorrow (Slicer-4.11.0-2020-02-26, revision 28794), …

Maybe that´s also the case in your situation?

Best,  
Markus

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