Open Inventor is an object-oriented 3D toolkit offering a
  comprehensive solution to interactive graphics programming problems.
  It presents a programming model based on a 3D scene database that
  dramatically simplifies graphics programming. It includes a rich set
  of objects such as cubes, polygons, text, materials, cameras, lights,
  trackballs, handle boxes, 3D viewers, and editors that speed up your
  programming time and extend your 3D programming capabilities.

  Open Inventor: 
      o is built on top of OpenGL 
      o defines a standard file format for 3D data interchange 
      o introduces a simple event model for 3D interaction 
      o provides animation objects called Engines 
      o provides high performance object picking 
      o is window system and platform independent 
      o supports PostScript printing 
      o encourages programmers to create new customized objects 
      o is fun to use