1. A method for rendering a computer-generated image for display, comprising the steps of: creating a first scene graph which represents the entire image, wherein the first scene graph is viewable by the user; storing the first scene graph in memory; creating a second scene graph which represents the same entire image as the first scene graph, wherein the first scene graph and the second scene graph each independently represents the entire image, the first scene graph is organized to be optimally viewed by a user whereas the second scene graph is organized to optimally render the image; storing the second scene graph in the memory; accepting a change to the first scene graph made by the user; changing the second scene graph to reflect the change made to the first scene graph; rendering the image for display according to the second scene graph, wherein the image is rendered only from the second scene graph and not from the first scene graph.