# Tracking Multiple Actors

**URL:** https://discourse.vtk.org/t/tracking-multiple-actors/5285
**Category:** Support
**Created:** [March 1, 2021, 4:20pm UTC](https://discourse.vtk.org/t/tracking-multiple-actors/5285 "2021-03-01T16:20:23Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Cliff](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/c/b38774/32.png) [@Cliff](https://discourse.vtk.org/u/Cliff)
#### Post date: [March 1, 2021, 4:20pm UTC](https://discourse.vtk.org/t/tracking-multiple-actors/5285/1 "2021-03-01T16:20:23Z")

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Hi all,

For an application I’m building I’d like to be able to track the relative pose and position of two vtkActors, I’me sure somewhere in the code there is the information I need but I can’t seem to find it!

To clarify what I want is for the user to be able to move two actors independently via vtkInteractorStyleTrackballActor and then at some point be able to calculate the relative movements so that I can calculate the distance between the vertices in the two datasets.

I already have the code for the distance calculation but when I interact with the data I can’t seem to be able to recover the movement.

Thanks in advance.

Cliff