Explore CMS open data and visualise detector events

iSpy WebGL

How to use the event display

The CMS event display (called iSpy) can be used to visualise in your browser collision data recorded by the CMS detector. Files of a custom type called .ig can be opened using iSpy. Each .ig file is in fact a collection containing numerous individual collision events.

This guide will take you through some of the basic functionality of the event display.

Top-row buttons

Each button comes with a tool-tip: hover over the button to know its functionality.

  • Open .ig files from the server.
  • and Navigate to previous and next events in the .ig file you loaded.
  • Returns the event display to its initial orientation. and Zoom in and out.
  • , and View the collision event along one of three axes.
  • and Switch between a perspective projection and an orthographic projection.
  • Use the settings button to invert the colours of the display or display the frame rate.


  • Click on the checkboxes to show or hide the CMS sub-detectors, particle tracks and hits, and more.