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Home < Documentation < Nightly < Modules < Watchdog

For the stable Slicer documentation, visit the 4.10 page.

Introduction and Acknowledgements

Contributors: Jaime Garcia Guevara (PerkLab, Queen's University), Andras Lasso (PerkLab, Queen's University)
Contact: Tamas Ungi, <email></email>

Cancer Care Ontario  

Module Description

Module for displaying warning message to the user if continuous update of tracked tool position or update of an image stream stops.

Demo video:

The module provides the following features:

  • Display of a warning message in any of the viewer window(s), at configurable size, color, and transparency
  • Sound feedback when tracking or imaging is stopped or resumed
  • All settings are saved with the scene and when the scene is loaded into Slicer the configured watchdog is activated automatically

Use Cases

Tool positions and/or images are typically acquired through OpenIGTLink from Plus Server ( or other compatible server. When an optically tracked tool gets out of the tracker's view or an electromagnetically tracked tool gets out of the tracking field then position updates stop. As a result, the tracked tool stops moving and/or the displayed image stops updating, but this may not be immediately visible to the operator. To make sure that stopping of real-time updates is not missed by the operator, the Watchdog module is configured to provide visual and/or audible warning.

Limitation: end of warning sounds may be clipped during replay, therefore users cannot fully rely on the audio feedback.


See this 1-minute video:

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