# How to get voxel coordinates(as in ITK snap ) from vtkimage viewer from mouse click

**URL:** https://discourse.vtk.org/t/how-to-get-voxel-coordinates-as-in-itk-snap-from-vtkimage-viewer-from-mouse-click/7607
**Category:** Support
**Created:** [January 10, 2022, 6:01am UTC](https://discourse.vtk.org/t/how-to-get-voxel-coordinates-as-in-itk-snap-from-vtkimage-viewer-from-mouse-click/7607 "2022-01-10T06:01:05Z")
**Posts on this page:** 1
**Page:** 1

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### Author: ![Sreerag](https://discourse.vtk.org/letter_avatar_proxy/v4/letter/s/ac8455/32.png) [@Sreerag](https://discourse.vtk.org/u/Sreerag)
#### Post date: [January 10, 2022, 6:01am UTC](https://discourse.vtk.org/t/how-to-get-voxel-coordinates-as-in-itk-snap-from-vtkimage-viewer-from-mouse-click/7607/1 "2022-01-10T06:01:05Z")

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Hello,  
I am trying to use ITK’s region growing algorithm for medical image segmentation. So to put the seedpoint i need exact voxel coordinates of the mouseclick position in my vtkimageviewer. So how can I get those voxel coordinates(as in ITK snap tool) from my vtkimage viewer. Currently I am able to get VTK World Coordinates using pick point picker . Now how to convert this vtk world coordinates to voxel coordinates as in ITK snap tool …  
Please help me with this information.