# Sign of markup point coordinates

**URL:** <https://discourse.slicer.org/t/sign-of-markup-point-coordinates/36554>\
**Category:** Support\
**Created:** [June 2, 2024, 12:24pm UTC](https://discourse.slicer.org/t/sign-of-markup-point-coordinates/36554 "2024-06-02T12:24:07Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![YLX](https://avatars.discourse-cdn.com/v4/letter/y/c57346/32.png) [@YLX](https://discourse.slicer.org/u/YLX)\
**Post date:** [June 2, 2024, 12:24pm UTC](https://discourse.slicer.org/t/sign-of-markup-point-coordinates/36554/1 "2024-06-02T12:24:07Z")

</div>

When selecting coordinate points in 3D Slicer software, you can see the specific values on the RSA axis. According to my observation, usually the RA axis is negative, while the S axis is positive, but in the output fscv file, all the three-dimensional coordinates have become positive numbers. How can I solve this problem.

 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/2/d/2d29d66fbc138aa00c2d65c29870bda5d5dde6f5.png)  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/8/5/854aade14d66f54ce8833ca2418ec45197d40479.png)

Operating system:  
Slicer version:5.7.0  
Expected behavior:  
Actual behavior:

---

<div class="post-metadata">

**Author:** ![Sunderlandkyl](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/sunderlandkyl/32/79987_2.png) [@Sunderlandkyl](https://discourse.slicer.org/u/Sunderlandkyl)\
**Post date:** [June 3, 2024, 1:45pm UTC](https://discourse.slicer.org/t/sign-of-markup-point-coordinates/36554/2 "2024-06-03T13:45:08Z")

</div>

Internally 3D Slicer represents data in RAS coordinate system.

When data is saved to file, it is written in LPS coordinates, so the first two components are multiplied by -1.