Geometry in the 3D space is described in ROOT by means of basic solids that can be joined, intersected or subtracted to create more complex shapes. The possibility to visualize 3D objects is very important: in ROOT the rendering engine is provided by the OpenGL library, that provides advanced visualization features and real-time animations.

Event display applications are an important application of 3D visualization. EVE is a ROOT module based on experiment-independent part of the ALICE and CMS event displays, using the ROOT GUI and the OpenGL rendering engine. An introduction to EVE can be found here.