# The coordinates of points in stl model after voxelization

**URL:** <https://discourse.slicer.org/t/the-coordinates-of-points-in-stl-model-after-voxelization/17515>\
**Category:** Support\
**Created:** [May 8, 2021, 2:58am UTC](https://discourse.slicer.org/t/the-coordinates-of-points-in-stl-model-after-voxelization/17515 "2021-05-08T02:58:29Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![wangyunning](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/wangyunning/32/14704_2.png) [@wangyunning](https://discourse.slicer.org/u/wangyunning)\
**Post date:** [May 8, 2021, 2:58am UTC](https://discourse.slicer.org/t/the-coordinates-of-points-in-stl-model-after-voxelization/17515/1 "2021-05-08T02:58:29Z")

</div>

Hello everyone, I am learning about computer-assisted spine surgery planning.in slicer, how to obtain the coordinates of points on the intersection line between the plane and the STL model.  
 ![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/4/3/43ce46c38ce3f5552503a98bd53bc0f18d5fad4f.png)

The positional relationship between the plane and the model is shown in the figure. The red line in the figure represents a plane perpendicular to the screen. I want to get the coordinates of this plane so that I can guide the path planning of the laminar grinding surgical robot.  
Sir, could you give me some guidance(@lassoan).

A little help appreciated!Thank you!

---

<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:** [May 13, 2021, 5:02am UTC](https://discourse.slicer.org/t/the-coordinates-of-points-in-stl-model-after-voxelization/17515/2 "2021-05-13T05:02:13Z")

</div>

You can use IntersectWithLine function in VTK - see this [post](https://discourse.slicer.org/t/intersection-between-markups-closed-curve-node-on-the-plane-and-a-line/11281/5). There are many examples in the [script repository](https://slicer.readthedocs.io/en/latest/developer_guide/script_repository.html) to show how you can set up a locator.

You can do much more sophisticated analysis of the pedicle screw trajectory, for example analyze bone density traversed by the screw (not just a line but an actual screw shape), as it is done in [Pedicle screw simulator extension](https://github.com/lassoan/PedicleScrewSimulator).