Abstract: In 3D large scale multi-resolution terrain rendering, an improved algorithm based on LOD control and visibility for crack removing was proposed. It is proved that quad-tree grid is restricted while the ratio of visible distance to grid extent is large than 3. In preprocess stage, cracks were classified to raise crack and dropped crack, and crack patches with the same size as cracks were generated and attached to the latter. In real-time rendering stage, no special calculation by CPU for restriction of level of detail or for crack removing between adjacent grids was needed. Example shows that the algorithm is simple, reduces additional patches about 75% than traditional skirt algorithm, and removes cracks efficiently.

Key words: restricted quad-tree grid, terrain rendering, multi-resolution, terrain crack, crack patch