Directional searching algorithm of Degenerate Quadtree Grid on spherical facet

Adjacent searching is the basis of spatial operations, and has become one of the key problems in the discrete global grid query & calculations. But the existing adjacent searching algorithm of Degenerate Quadtree Grid (DQG) on spherical facet can only find neighbor cells around a target cell rather than the cells along a given direction. In order to overcome this deficiency, a directional searching algorithm of DQGs is presented in this paper in details. Finally, an experiment about the directional searching results and efficiency of this algorithm is given. It demonstrates that the searching results match well with spherical curves and the efficiency is the same as the adjacent searching algorithm, this algorithm is validity and feasibility.