# vtkLabelPlacementMapper with coincident points

**URL:** https://discourse.vtk.org/t/vtklabelplacementmapper-with-coincident-points/16297
**Category:** Support
**Created:** [February 20, 2026, 3:34pm UTC](https://discourse.vtk.org/t/vtklabelplacementmapper-with-coincident-points/16297 "2026-02-20T15:34:13Z")
**Posts on this page:** 3
**Page:** 1

<div class="post-metadata">

### Author: ![raungst](https://discourse.vtk.org/user_avatar/discourse.vtk.org/raungst/32/1965_2.png) [@raungst](https://discourse.vtk.org/u/raungst)
#### Post date: [February 20, 2026, 3:34pm UTC](https://discourse.vtk.org/t/vtklabelplacementmapper-with-coincident-points/16297/1 "2026-02-20T15:34:13Z")

</div>

Hi,

I’m currently using vtkLabelPlacementMapper to label a bunch of points in my scene. My trouble is that if I label points that are coincident, vtkLabelPlacementMapper is moving the points so they don’t overlap anymore. I realize this is part of the purpose of this mapper, but is there anyway I can have it leave the points alone even if the labels end up not being readable because their on top of each other?

Thanks!  
Robby

---

<div class="post-metadata">

### Author: ![lassoan](https://discourse.vtk.org/user_avatar/discourse.vtk.org/lassoan/32/50_2.png) [@lassoan](https://discourse.vtk.org/u/lassoan)
#### Post date: [February 21, 2026, 4:21pm UTC](https://discourse.vtk.org/t/vtklabelplacementmapper-with-coincident-points/16297/2 "2026-02-21T16:21:04Z")

</div>

We ran into the same issue in 3D Slicer. My conclusion was that the implementation of vtkPointSetToLabelHierarchy/vtkLabelPlacementMapper is not just buggy but incomplete. Among other things, label position perturbation is not fully implemented and its current behavior is basically random.

There is no on/off switch for the label position perturbation (it is one of the many things that would need to be implemented), but we applied the following workaround: in vtkPointSetToLabelHierarchy set maximum depth to a large number (e.g., 10) and in vtkLabelPlacementMapper set PlaceAllLabelsOn:

> <https://github.com/Slicer/Slicer/blob/c792b1fb8445a8c91282b33bcaa037091130eb85/Modules/Loadable/Markups/VTKWidgets/vtkSlicerMarkupsWidgetRepresentation2D.cxx#L83-L92>

There is an issue submitted for this in 2017:

[https://gitlab.kitware.com/vtk/vtk/-/issues/17097](https://gitlab.kitware.com/vtk/vtk/-/issues/17097)

---

<div class="post-metadata">

### Author: ![raungst](https://discourse.vtk.org/user_avatar/discourse.vtk.org/raungst/32/1965_2.png) [@raungst](https://discourse.vtk.org/u/raungst)
#### Post date: [February 21, 2026, 5:00pm UTC](https://discourse.vtk.org/t/vtklabelplacementmapper-with-coincident-points/16297/3 "2026-02-21T17:00:49Z")

</div>

Thank you! Setting the maximum depth to 10 looks like it fixed it for me.