# How to pick a point in volume rendering?

**URL:** <https://discourse.slicer.org/t/how-to-pick-a-point-in-volume-rendering/35120>\
**Category:** Support\
**Created:** [March 27, 2024, 8:48am UTC](https://discourse.slicer.org/t/how-to-pick-a-point-in-volume-rendering/35120 "2024-03-27T08:48:00Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![zhang-qiang-github](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/zhang-qiang-github/32/9019_2.png) [@zhang-qiang-github](https://discourse.slicer.org/u/zhang-qiang-github)\
**Post date:** [March 27, 2024, 8:48am UTC](https://discourse.slicer.org/t/how-to-pick-a-point-in-volume-rendering/35120/1 "2024-03-27T08:48:00Z")

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In 3D slicer, 3D visualization used the volume rendering. And 3D slicer can pick a point from volume rendering. For example:

![image](https://us1.discourse-cdn.com/flex002/uploads/slicer/original/3X/6/c/6c2ba3cf175f64a8da03a03298aecaafadbdc3c3.jpeg)

Is `vtkPropPicker` or `vtkCellPicker` userd? I can not pick a 3D point from volume rendering.

Any suggestion is appreciated~~~

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**Author:** ![cpinter](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/cpinter/32/7995_2.png) [@cpinter](https://discourse.slicer.org/u/cpinter)\
**Post date:** [April 1, 2024, 12:24pm UTC](https://discourse.slicer.org/t/how-to-pick-a-point-in-volume-rendering/35120/2 "2024-04-01T12:24:35Z")

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I’d probably try starting from this code:

> <https://github.com/Slicer/Slicer/blob/3903a95c38730e522630569b114825dd0d7c9532/Libs/MRML/DisplayableManager/vtkMRMLThreeDViewInteractorStyle.cxx#L170-L183>