Abstract: Shape distortion in certain degree will appear during terrain polygon mesh simplification based on the original geomipmapping algorithm without maintaining terrain feature points, such as points on hilltops and ridges.The geomipmapping algorithm of rendering terrain with features being maintained is proposed to solve the above problem.Feature points on hilltops are extracted by immune particle swarm network algorithm and points on ridges are found by ant colony fuzzy clustering analysis.Patches containing feature points are rendered in hierarchical higher-resolution while lower-resolution is adapted to render the patches without feature points.Method of eliminating cracks between patches is proposed for above geomipmapping terrain features maintained algorithm.Experimental results show that this algorithm can maintain the terrain features while the geomipmapping algorithm possesses high efficiency.Terrain shape distortion is reduced.Popping during viewpoint moving is also decreased at certain extent.