# vtkOpenGLSphereMapper not working (or perhaps not understood how it works)

**URL:** https://discourse.vtk.org/t/vtkopenglspheremapper-not-working-or-perhaps-not-understood-how-it-works/5665
**Category:** Development
**Created:** [April 29, 2021, 12:42pm UTC](https://discourse.vtk.org/t/vtkopenglspheremapper-not-working-or-perhaps-not-understood-how-it-works/5665 "2021-04-29T12:42:12Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Guillaume\_Gillet](https://discourse.vtk.org/user_avatar/discourse.vtk.org/guillaume_gillet/32/3114_2.png) [@Guillaume\_Gillet](https://discourse.vtk.org/u/Guillaume_Gillet)
#### Post date: [April 29, 2021, 12:42pm UTC](https://discourse.vtk.org/t/vtkopenglspheremapper-not-working-or-perhaps-not-understood-how-it-works/5665/1 "2021-04-29T12:42:12Z")

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So i wanted to make some memory used and time of rendering tests with 3D points, to display them i needed them to be spheres, i first used the glyph3d Filter but it turns out when you go over a million points it takes way too much memory, so i tried the vtkGlyph3D mapper and it was a blast, clearly faster, bu i would love the imposter technique to work on my projet so i can compare the speeds and memory sizes. So i tried giving my point dataset that i gave to the other filters to the mapper, turns out it doesn’t display anything, i tried a lot of things, and it only shows them when i add some 3d geometry before the mapper.  
Am I missing something? Or is there no other ways to do so? Anyway thanks for reading and for the help if you provide some!