We have seen some examples of OpenGL in action on the web and on Android. These examples are constructed to illustrate OpenGL concepts. In the real world you will not see hand typed vertex data. These four techniques are much more likely.
A modeling tool, such as Blender or 3ds Max is used to generate the components of a scene, which are then loaded into the program and provided to OpenGL.
An API such as Three.js can be used to generate a wide range of WebGL scenes. Three.js also includes loaders for a few file formats.
Scenes can be generated computationally. The starting example from this talk generates and draws the electric field lines for a user defined charge configuration.
OpenGL and imagination can give a lift to data displays.