Multi-scale two-dimensional Hilbert curve is constructed, and specially the scale dimension is treated as the third dimension. The new structure embodies the multi-level characteristics and overcomes the drawback of Z sequence coding pattern, thus improving the continuity of the curve and advancing the spatial retrieval efficiency. The authors conducted two kinds of experiments based on the quad-tree model to compare the retrieval efficiency of Hilbert curve and Z curve. The consequence indicates that the multi-scale Hilbert curve performs better than Z curve, and the improvement on different data distributions vary from 15% to 30%.

To supplement the deficiency of the latitude and longitude existed as location code, such as complex description, non-regional characteristics and complex computation, a globe spatial grid reference system is constructed based on GeoSOT from Peking University. The grid system, built from a perfect quadtree with one degree, one minute and one second grid, could be fit for air-earth joint action. It designs a simple and practical location coding method, which also supports distance simple calculation. It could realize multi-source spatial data integrated retrieval, and develop methods of efficient code operation, framework of spatial computing, and 3D-earth grid system. Globe Spatial Grid Reference System will definitely play an important role in the future of big spatial data applications.