# How does 3dslicer read external marker coordinates

**URL:** <https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192>\
**Category:** Support\
**Tags:** registration\
**Created:** [April 20, 2021, 3:30am UTC](https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192 "2021-04-20T03:30:40Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![wujie](https://avatars.discourse-cdn.com/v4/letter/w/dbc845/32.png) [@wujie](https://discourse.slicer.org/u/wujie)\
**Post date:** [April 20, 2021, 3:30am UTC](https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192/1 "2021-04-20T03:30:41Z")

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How does 3dslicer read external marker coordinates

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**Author:** ![ungi](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ungi/32/78573_2.png) [@ungi](https://discourse.slicer.org/u/ungi)\
**Post date:** [April 20, 2021, 10:33pm UTC](https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192/2 "2021-04-20T22:33:46Z")

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Slicer communicates with position trackers through the OpenIGTLink communication protocol. You need to install the SlicerOpenIGTLink extension for that. I also recommend installing SlicerIGT extension, if you use real time trackers. There are some useful tutorials on this page: [User tutorial | SlicerIGT](http://www.slicerigt.org/wp/user-tutorial/)  
Some of them are a bit outdated, but still useful.  
PLUS is a great tool to read any tracker and translate the real time information to OpenIGTLink and send in real time to Slicer: [https://plustoolkit.github.io/](https://plustoolkit.github.io/)

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**Author:** ![wujie](https://avatars.discourse-cdn.com/v4/letter/w/dbc845/32.png) [@wujie](https://discourse.slicer.org/u/wujie)\
**Post date:** [April 21, 2021, 7:45am UTC](https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192/3 "2021-04-21T07:45:03Z")

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Thanks your reply, I have installed the OpenIGTLink and communication protocol and PLUS,could you please tell me the examples of read external marker coordinates?

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**Author:** ![ungi](https://sea2.discourse-cdn.com/flex002/user_avatar/discourse.slicer.org/ungi/32/78573_2.png) [@ungi](https://discourse.slicer.org/u/ungi)\
**Post date:** [April 21, 2021, 2:22pm UTC](https://discourse.slicer.org/t/how-does-3dslicer-read-external-marker-coordinates/17192/4 "2021-04-21T14:22:53Z")

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You need to specify which tracker device you are using. Here is a list of devices already supported by PLUS: [Plus applications user manual: Device set configuration](http://perk-software.cs.queensu.ca/plus/doc/nightly/user/Configuration.html)  
Can you find your device in the list?