# How to represent multiple actors with one single actor?

**URL:** https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150
**Category:** Support
**Created:** [February 6, 2021, 11:42am UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150 "2021-02-06T11:42:27Z")
**Posts on this page:** 5
**Page:** 1

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### Author: ![11114](https://discourse.vtk.org/user_avatar/discourse.vtk.org/11114/32/2979_2.png) [@11114](https://discourse.vtk.org/u/11114)
#### Post date: [February 6, 2021, 11:42am UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150/1 "2021-02-06T11:42:27Z")

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my problem is I have got a 3D hammer model that formed by multiple cells which means multiple actors and mappers should be present in the scene , so is there any way I can make these hammer represent by a single actor(i.e., use one actor to represent multiple actors) ?

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### Author: ![Sebastien\_Jourdain](https://discourse.vtk.org/user_avatar/discourse.vtk.org/sebastien_jourdain/32/100_2.png) [@Sebastien\_Jourdain](https://discourse.vtk.org/u/Sebastien_Jourdain)
#### Post date: [February 6, 2021, 8:22pm UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150/2 "2021-02-06T20:22:54Z")

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I’m not sure why you have 1 cell per actor. Usually when we render a dataset (vtkPolyData) those have thousands or millions of cells for only one mapper/actor.

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### Author: ![AlexG](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/a/ecc23a/32.png) [@AlexG](https://discourse.vtk.org/u/AlexG)
#### Post date: [February 8, 2021, 9:29am UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150/3 "2021-02-08T09:29:25Z")

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You can try to use _vtkAssembly_ to combine all actors to one assembly which then can be rendered/moved at once.

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### Author: ![11114](https://discourse.vtk.org/user_avatar/discourse.vtk.org/11114/32/2979_2.png) [@11114](https://discourse.vtk.org/u/11114)
#### Post date: [February 8, 2021, 2:21pm UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150/4 "2021-02-08T14:21:28Z")

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ok ,thanks sir ,and i am new to VTK, i am kinda confused about the vtkpolydata and vtkunstructuredGrid , it seems they are interchangeable using filter , so what is the main differences between these two

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### Author: ![will.schroeder](https://discourse.vtk.org/user_avatar/discourse.vtk.org/will.schroeder/32/233_2.png) [@will.schroeder](https://discourse.vtk.org/u/will.schroeder)
#### Post date: [February 8, 2021, 2:41pm UTC](https://discourse.vtk.org/t/how-to-represent-multiple-actors-with-one-single-actor/5150/5 "2021-02-08T14:41:23Z")

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vtkUnstructuredGrid can represent any cell type, including especially 3D linear and nonlinear cells.

vtkPolyData was originally designed to interface with VTK’s surface-based rendering subsystem, and for that reason represents 0D, 1D, and 2D cells, such as polygonal meshes.