In a computer image generation system, the number of vertices which define polygons is augmented in real time for providing finer detail and for effecting smooth level of detail transition. Augmented vertices may have components that are statistically derived in which case it is not necessary to store and/or predefine them. Alternatively, some vertex components may have predetermined values derived from mapping data or from other deterministic sources and may be stored in compact form. Processing polygons defined by the augmented vertices along with the original vertices may be used for displaying the finer detail. Statistically derived finer detail is especially suited for providing non-specific detail to features such as terrain and bodies of water, while deterministic data allows highly accurate representations of specific 'real world' locations. Vertex augmentation may be controlled by the following breakupcriteria: range from the viewpoint, angle from the viewpoint boresight, desired maximum error or other criteria and combinations thereof.