1. A computer-implemented method for rendering three-dimensional images using a level graph, the method comprising: accessing the level graph, the level graph comprising a first node, a second node, and a target node, wherein the second node and target node are descendants of the first node, and wherein the first node comprises a first scene description data, the second node comprises a first variation data, and the target node comprises a second variation data; receiving a selection of the target node for computation; determining ancestors of the target node, wherein the ancestors of the target node comprises the first node and the second node; determining a linearization of the ancestors of the target node, the linearization comprising an order of the ancestors of the target node; initializing a scene description using the first scene description data of the first node; applying the first variation of the second node to the scene description, based on the linearization, to produce an updated scene description; applying the second variation of the target node to the updated scene description to produce a final scene description; and rendering an image based on the final scene description.