# Performance degrade for more than 10000 actor

**URL:** https://discourse.vtk.org/t/performance-degrade-for-more-than-10000-actor/5683
**Category:** Support
**Created:** [May 2, 2021, 4:47pm UTC](https://discourse.vtk.org/t/performance-degrade-for-more-than-10000-actor/5683 "2021-05-02T16:47:37Z")
**Posts on this page:** 1
**Showing post:** 7

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### 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: [May 4, 2021, 1:52am UTC](https://discourse.vtk.org/t/performance-degrade-for-more-than-10000-actor/5683/7 "2021-05-04T01:52:15Z")

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You should keep the number of actors preferably below a few hundred. If you want to display thousands of small spheres then you can use a glyph filter (such as [vtkGlyph3D](https://vtk.org/doc/nightly/html/classvtkGlyph3D.html)) and render it using a single actor; or for even better performance, use a [glyph mapper](https://vtk.org/doc/nightly/html/classvtkGlyph3DMapper.html).

I’m not sure if there is a widget that you can use for individual picking and moving of individual spheres. In 3D Slicer, we had to implement our own widget for this, and the performance is good with a few 10k points. If you need to interact with many point glyphs from a C++ or Python application with Qt GUI then you may consider using 3D Slicer as a platform, especially if you work in the medical imaging domain.

[![](https://discourse.vtk.org/uploads/default/original/2X/9/9ad1817470e21b5a81251e2cbb924322190ad9f3.jpeg "Slicer markups manipulation performance improvement") ](https://www.youtube.com/watch?v=dXV8-Z8Z_NM)

You may find this and related topics relevant:

> [@picking glyphs vtkGlyph3DMapper](https://discourse.vtk.org/t/picking-glyphs-vtkglyph3dmapper/1618):
>
> Can anyone suggest what’s the right picker to use for finding out the top-most glyph at a glyph from a vtkGlyph3DMapper? I tried to use vtkCellPicker, but it never seems to return any hits from the glyphs, only from other actors. There’s an old [mailing list post](http://vtk.1045678.n5.nabble.com/vtkCellPicker-not-working-with-vtkGlyph3DMapper-td5721564.html) that seems to suggest using vtkGlyph3D, which I can’t do because I need to independently rotate and scale the glyphs. This [merge request](https://gitlab.kitware.com/vtk/vtk/commit/6327999ee944a6861bc02261773d642e9f7cb90c) strongly implies that it’s possible to pick cells, but maybe not with vtkCellPicker? The fact t…

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