Patent ID: 7436405

Claim:
A computer implemented method of providing varying levels of detail in terrain rendering, the method comprising: providing representations of plural levels of detail of a terrain, where each level represents a regular grid; determining a viewpoint of a viewer; caching a terrain view in a set of nested regular grids obtained from the plural levels as a function of distance from the viewpoint, each regular grid having a two-dimensional array of vertices, the number of vertices in each dimension of size n; determining transition regions as of boundary grids within each of the nested regular grids, the transition regions width w determined by the equation w=min(n/10, min_width) and wherein min_width>=2; rendering the set of nested regular grids; and incrementally refilling the set of nested regular grids as the viewpoint moves relative to the terrain; wherein vertices of a regular grid comprise x, y, z, and z c coordinates, wherein z coordinates represent terrain elevation values for a level and z c coordinates represent terrain elevation values of a next coarser level, and the z c value is used in the transition region in transition morphing between adjacent levels of the set of nested regular grids such that a z′ value is used to represent the terrain elevation at each x, y coordinate in the transition region, and the z′ coordinate is determined by an equation z′=(1−α)z+αz c , where α is a blend parameter that evaluates from zero to one in the transition region so as to facilitate smooth blending between levels; and wherein the transition morphing is calculated in a graphical processing unit via a vertex shader.