Interactive graphics for the CMS experiment at the LHC

The ability to visualise the CMS detector and its response to physics processes is of great importance, both in the design evaluation and data analysis phases of the experi- ment. We describe the visualisation requirements of CMS and the implementation of the CMS interactive detector and event visualisation program, known as CMSCAN, which supports 3D viewing of the detector and events, as well as abstracted images, such as lego plots. It provides a high level of user interactivity, such as rotation, translation, magnification, and visibility of the image, and communicates with the reconstruction program to allow the user to control the data processing and analysis.