UPDATING ANIMATED IMAGES REPRESENTED BY SCENE GRAPHS

Each frame in an animated graphics sequence has a hierarchical scene graph. Graph elements have creation timestamps that mark them as dirty, requiring rendering, or constant, not requiring rendering anew for the current frame. If an aggregate element is constant, it is rendered as a whole, without investigating its child elements. If dirty elements meet certain criteria, they are merged for rendering as a single unit. In this way, the scene areas to be rendered have variable positions and sizes.