GIMP wouldn’t help you here. Unless it can export obj/fbx files I created a plane in Silo with many divisions and exported as an fbx. When I show the wireframe of the model in the video you can see how many vertices it has. You can use maya, max, blender or Silo (which is on sale as part of a mac bundle here for $20 …http://www.macheist.com/#overview).
You can’t create that in the editor at the moment. I’m thinking of creating some plugins which allow you to make custom in the editor.