Abstract: Massive three-dimensional(3D) terrain real-time rendering technology is one of the core technology and difficulties for 3D visualization system. Aiming at the problems of strong tile level constraint and low rendering efficiency which exist in traditional methods, this paper presents a new level constraints removed algorithm to avoid the crack in massive 3D terrain. Firstly, it builds a multi resolution representation structure of quad-tree terrain including terrain tile corner and edge neighbor relationship. Then the split or merged state for the nodes of quad-tree is updated dynamicly on the basis of LoD control rule. Finally, the linear interpolation algorithm is used to modify the tile elevation of neighbor relations in quad-tree to eliminate terrain cracks. The experiment on massive mountainous terrain data shows that the algorithms we proposed are effective and efficient.

Key words: terrain visualization, quad-tree, level constraints removed, avoiding crack