# Model Registration Using Singular Points
**URL:** https://discourse.slicer.org/t/model-registration-using-singular-points/8711
**Category:** Support
**Tags:** transforms, 3d-model, markups-fiducials
**Created:** [October 8, 2019, 7:44pm UTC](https://discourse.slicer.org/t/model-registration-using-singular-points/8711 "2019-10-08T19:44:53Z")
**Posts on this page:** 2
**Page:** 1
### Author:  [@David\_Asgar-Deen](https://discourse.slicer.org/u/David_Asgar-Deen)
#### Post date: [October 8, 2019, 7:44pm UTC](https://discourse.slicer.org/t/model-registration-using-singular-points/8711/1 "2019-10-08T19:44:53Z")
Operating system: Windows 10 build 17763.775
Slicer version: 4.10.2
Expected behavior: I currently have 2 main transforms within my scene: NeedleToReference and PhantomToReference. Within the NeedleToReference transform, I have another transformation that maps the NeedleTipToNeedle. I would like to place some spherical models inside the phantom. As I can locate the center of the sphere position within the phantom using the needle tip I was thinking of placing fiducial points in 3D space using the needle tip, finding the linear transform between the marker and my phantom tracker, and placing a spherical model in the Transform Hierarchy in the Data module.
Actual behavior: I am currently unsure about how to calculate the transformation between the fiducial point relative to the phantom position sensor.
Any help on the issue would be greatly appreciated!
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### Author:  [@lassoan](https://discourse.slicer.org/u/lassoan)
#### Post date: [October 8, 2019, 8:08pm UTC](https://discourse.slicer.org/t/model-registration-using-singular-points/8711/2 "2019-10-08T20:08:35Z")
The process for landmark-based object registration using a tracked stylus is described in detail in [SlicerIGT tutorials](http://www.slicerigt.org/wp/user-tutorial/) (“Pivot calibration” and “Landmark registration”).